i386: Allow copy relocs for building PIE

i386: Allow copy relocs for building PIE

This patch allows copy relocs for R_386_GOTOFF relocations in PIE.  For

extern int glob_a;
int foo ()
{
  return glob_a;
}

compiler now can optimize it from

	call	__x86.get_pc_thunk.ax
	addl	$_GLOBAL_OFFSET_TABLE_, %eax
	movl	glob_a@GOT(%eax), %eax
	movl	(%eax), %eax
	ret

to

	call	__x86.get_pc_thunk.ax
	addl	$_GLOBAL_OFFSET_TABLE_, %eax
	movl	glob_a@GOTOFF(%eax), %eax
	ret

bfd/

	PR ld/18289
	* elf32-i386.c (elf_i386_link_hash_entry): Add gotoff_ref.
	(elf_i386_link_hash_newfunc): Initialize gotoff_ref to 0.
	(elf_i386_create_dynamic_sections): Always allow copy relocs for
	building executables.
	(elf_i386_copy_indirect_symbol): Also copy gotoff_ref.
	(elf_i386_check_relocs): Set gotoff_ref for R_386_GOTOFF.
	(elf_i386_adjust_dynamic_symbol): Also allocate copy relocs for
	PIE and R_386_GOTOFF.
	(elf_i386_relocate_section): Allow R_386_GOTOFF in executable.

ld/testsuite/

	PR ld/18289
	* ld-i386/copyreloc-lib.c: New file.
	* ld-i386/copyreloc-main.S: Likewise.
	* ld-i386/copyreloc-main.out: Likewise.
	* ld-i386/copyreloc-main1.rd: Likewise.
	* ld-i386/copyreloc-main2.rd: Likewise.
	* ld-i386/dummy.c: Likewise.
	* ld-i386/pr17689.out: Likewise.
	* ld-i386/pr17689.rd: Likewise.
	* ld-i386/pr17689a.c: Likewise.
	* ld-i386/pr17689b.S: Likewise.
	* ld-i386/pr17827.rd: Likewise.
	* ld-i386/pr17827ver.rd: Likewise.
	* ld-i386/i386.exp: Run copyreloc tests.