ELF: Call check_relocs after opening all inputs

ELF: Call check_relocs after opening all inputs

For all ELF targers, call check_relocs after opening all inputs and
garbage collection.  Since the symbol resolution is known, check_relocs
can be simplified.  Also garbage collection doesn't need to undo what
check_relocs has done for symbols which have been garbage collected.
Since ELF targets never see the removed sections, gc_sweep_hook can be
removed from elf_backend_data and we can avoid GOT/PLT with garbage
collection now.

Set link_info.check_relocs_after_open_input to TRUE for all linker
targets which use ELF linker and update garbage collection tests to
remove unused GOT section.

ldemul_after_check_relocs is added for powerpc to support --secure-plt,
--bss-plt and --sdata-got.

Tested natively without regressions on i686, x86-64 and x32.  Tested
cross binutils on x86-64 without regressions for aarch64-linux,
alpha-linux, arm-linux, bfin-elf, cr16-elf, cris-elf, crx-elf, frv-linux,
hppa64-linux, hppa-linux, ia64-linux, lm32-elf, m32r-elf, m68k-linux,
mcore-elf, metag-elf, microblaze-linux, mips-linux, mmix, mn10300-elf,
nds32le-linux, nios2-linux, or1k-elf, powerpc64-linux, powerpc-linux,
riscv32-linux, riscv64-linux, s390-linux, s390x-linux, score-elf,
sh3-linux, sparc64-linux, sparc-linux, tic6x-elf, tilegx-linux,
tilepro-linux, vax-linux, x86_64-mingw32 and xtensa-linux.

bfd/

	* elf-bfd.h (elf_backend_data): Remove gc_sweep_hook.
	* elf32-arm.c (elf32_arm_gc_sweep_hook): Removed.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-bfin.c (bfin_gc_sweep_hook): Likewise.
	(bfinfdpic_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-cr16.c (elf32_cr16_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-cris.c (cris_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-hppa.c (elf32_hppa_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-lm32.c (lm32_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-m32r.c (m32r_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-m68k.c (elf_m68k_got_entry): Remove elf_m68k_gc_sweep_hook
	from comments.
	(elf_m68k_remove_got_entry_type): Removed.
	(elf_m68k_find_got_entry_ptr): Likewise.
	(elf_m68k_remove_got_entry): Likewise.
	(elf_m68k_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-mcore.c (mcore_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-metag.c (elf_metag_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-microblaze.c (elf_backend_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-mips.c (elf_backend_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-nds32.c (nds32_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-nios2.c (nios2_elf32_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-or1k.c (or1k_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-ppc.c (ppc_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-s390.c (elf_s390_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-sparc.c (elf_backend_gc_sweep_hook): Likewise.
	* elf32-tic6x.c (elf32_tic6x_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-tilegx.c (elf_backend_gc_sweep_hook): Likewise.
	* elf32-tilepro.c (tilepro_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-vax.c (elf_vax_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf32-xtensa.c (elf_xtensa_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf64-alpha.c (elf64_alpha_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf64-mips.c (elf_backend_gc_sweep_hook): Likewise.
	* elf64-mmix.c (mmix_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf64-ppc.c (elf_backend_gc_sweep_hook): Likewise.
	(ppc64_elf_gc_sweep_hook): Likewise.
	* elf64-s390.c (elf_s390_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elf64-sparc.c (elf_backend_gc_sweep_hook): Likewise.
	* elf64-tilegx.c (elf_backend_gc_sweep_hook): Likewise.
	* elflink.c (elf_link_add_object_symbols): Don't call
	_bfd_elf_link_check_relocs here.
	(gc_sweep_hook_fn): Removed.
	(elf_gc_sweep): Remove gc_sweep_hook.
	* elfnn-aarch64.c (elfNN_aarch64_gc_sweep_hook): Removed.
	(elf_backend_gc_sweep_hook): Likewise.
	* elfnn-riscv.c (riscv_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elfxx-mips.c (_bfd_mips_elf_gc_sweep_hook): Likewise.
	* elfxx-mips.h (_bfd_mips_elf_gc_sweep_hook): Likewise.
	(elf_backend_gc_sweep_hook): Likewise.
	* elfxx-sparc.c (_bfd_sparc_elf_gc_sweep_hook): Likewise.
	* elfxx-sparc.h (_bfd_sparc_elf_gc_sweep_hook): Likewise.
	* elfxx-target.h (elf_backend_gc_sweep_hook): Likewise.
	(elfNN_bed): Remove elf_backend_gc_sweep_hook.
	* elfxx-tilegx.c (tilegx_elf_gc_sweep_hook): Removed.
	* elfxx-tilegx.h (tilegx_elf_gc_sweep_hook): Likewise.

ld/

	* emulparams/elf32_x86_64.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Removed.
	* emulparams/elf_i386_be.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/elf_i386_chaos.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/elf_i386_ldso.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/elf_i386_vxworks.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/elf_iamcu.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/elf_k1om.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/elf_l1om.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/elf_x86_64.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/i386lynx.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/i386moss.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/i386nto.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/i386nw.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/shelf.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/shelf32.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/shelf_nto.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/shelf_vxworks.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/shlelf32_linux.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/shlelf_linux.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emulparams/shlelf_nto.sh (CHECK_RELOCS_AFTER_OPEN_INPUT):
	Likewise.
	* emultempl/aarch64elf.em (gld${EMULATION_NAME}_before_parse):
	Set link_info.check_relocs_after_open_input to TRUE.
	* emultempl/armelf.em (gld${EMULATION_NAME}_before_parse):
	Likewise.
	* emultempl/scoreelf.em (gld${EMULATION_NAME}_before_parse):
	Likewise.
	* emultempl/aix.em (ld_${EMULATION_NAME}_emulation): Add
	after_parse_default.
	* emultempl/armcoff.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/beos.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/generic.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/gld960.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/gld960c.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/lnk960.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/m68kcoff.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/msp430.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/pe.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/pep.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/sunos.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/ticoff.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/vanilla.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Always
	set link_info.check_relocs_after_open_input to TRUE.
	(ld_${EMULATION_NAME}_emulation): Add $LDEMUL_AFTER_CHECK_RELOCS.
	* emultempl/linux.em (gld${EMULATION_NAME}_before_parse):
	Set link_info.check_relocs_after_open_input to TRUE.
	(ld_${EMULATION_NAME}_emulation): Add after_check_relocs_default.
	* emultempl/mmix-elfnmmo.em (mmix_before_parse): New function.
	(LDEMUL_BEFORE_PARSE): New.
	* emultempl/mmixelf.em (elfmmix_before_parse): Replace
	gld${EMULATION_NAME}_before_parse with mmix_before_parse.
	* emultempl/ppc32elf.em (ppc_after_open): Renamed to ...
	(ppc_after_check_relocs): This.  Call after_check_relocs_default
	instead of gld${EMULATION_NAME}_after_open.
	(LDEMUL_AFTER_OPEN): Removed.
	(LDEMUL_AFTER_CHECK_RELOCS): New.
	* ldemul.c (ldemul_after_check_relocs): New.
	(after_check_relocs_default): Likewise.
	* ldemul.h (ldemul_after_check_relocs): Likewise.
	(after_check_relocs_default): Likewise.
	(ld_emulation_xfer_struct): Add after_check_relocs.
	* ldlang.c (lang_process): Call ldemul_after_check_relocs after
	lang_check_relocs.
	* testsuite/ld-aarch64/gc-got-relocs.d: Don't expect GOT section.
	* testsuite/ld-aarch64/gc-tls-relocs.d: Likewise.
	* testsuite/ld-cris/tls-gc-68.d: Likewise.
	* testsuite/ld-cris/tls-gc-69.d: Likewise.
	* testsuite/ld-cris/tls-gc-70.d: Likewise.
	* testsuite/ld-cris/tls-gc-75.d: Likewise.
	* testsuite/ld-cris/tls-gc-79.d: Likewise.
	* testsuite/ld-mmix/bpo-10.d: Don't expect .MMIX.reg_contents
	section.