Add "-z call-nop=PADDING" option to ld

Add "-z call-nop=PADDING" option to ld

The ld linker can transform indirect call to a locally defined function,
foo, via its GOT slot, to either "NOP call foo" or "call foo NOP" where
NOP is a 1-byte NOP padding.  This patch adds a "-z call-nop=PADDING"
option to x86 ld to control 1-byte NOP padding for x86 call instruction.
PADDING is one of prefix-addr, prefix-nop, suffix-nop, prefix-NUMBER or
suffix-NUMBER.

bfd/

	* elf32-i386.c (elf_i386_convert_load): Use call_nop_byte and
	check call_nop_as_suffix for 1-byte NOP padding to pad call.
	* elf64-x86-64.c (elf_x86_64_convert_load): Likewise.

include/

	* bfdlink.h (bfd_link_info): Add call_nop_as_suffix and
	call_nop_byte.

ld/

	* ld/ld.texinfo: Document "-z call-nop=PADDING" option.
	* emulparams/call_nop.sh: New file.
	* emulparams/elf_i386_be.sh: Source
	${srcdir}/emulparams/call_nop.sh.
	* emulparams/elf_i386_chaos.sh: Likewise.
	* emulparams/elf_i386_ldso.sh: Likewise.
	* emulparams/elf_i386_vxworks.sh: Likewise.
	* emulparams/elf_iamcu.sh: Likewise.
	* emulparams/elf_k1om.sh: Likewise.
	* emulparams/elf_l1om.sh: Likewise.
	* emulparams/elf_x86_64.sh: Likewise.
	* emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Set
	link_info.call_nop_byte if $CALL_NOP_BYTE isn't empty.

ld/testsuite/

	* ld-i386/call3.s: New file.
	* ld-i386/call3a.d: Likewise.
	* ld-i386/call3b.d: Likewise.
	* ld-i386/call3c.d: Likewise.
	* ld-i386/call3d.d: Likewise.
	* ld-i386/call3e.d: Likewise.
	* ld-i386/call3f.d: Likewise.
	* ld-i386/call3g.d: Likewise.
	* ld-i386/call3h.d: Likewise.
	* ld-i386/load1-nacl.d: Likewise.
	* ld-x86-64/call1.s: Likewise.
	* ld-x86-64/call1a.d: Likewise.
	* ld-x86-64/call1b.d: Likewise.
	* ld-x86-64/call1c.d: Likewise.
	* ld-x86-64/call1d.d: Likewise.
	* ld-x86-64/call1e.d: Likewise.
	* ld-x86-64/call1f.d: Likewise.
	* ld-x86-64/call1g.d: Likewise.
	* ld-x86-64/call1h.d: Likewise.
	* ld-x86-64/call1i.d: Likewise.
	* ld-x86-64/load1a-nacl.d: Likewise.
	* ld-x86-64/load1b-nacl.d: Likewise.
	* ld-x86-64/load1c-nacl.d: Likewise.
	* ld-x86-64/load1d-nacl.d: Likewise.