PowerPC64 GOT indirect to GOT relative optimisation

PowerPC64 GOT indirect to GOT relative optimisation

This implements an optimisation that converts sequences like
  addis r9,r2,sym@got@ha
  ld r3,sym@got@l(r9)
to
  addis r9,r2,sym@toc@ha
  addi r3,r9,sym@toc@l
when "sym" is locally defined and can't be overridden.

bfd/
	* elf64-ppc.c (struct ppc64_elf_obj_tdata): Add has_gotrel.
	(struct _ppc64_elf_section_data): Likewise.
	(ppc64_elf_check_relocs): Set above fields.
	(ppc64_elf_edit_toc): Add a pass over GOT relocs.
	(ppc64_elf_relocate_section): Edit GOT indirect to GOT relative
	when possible.
ld/
	* testsuite/ld-powerpc/elfv2exe.d: Update.
	* testsuite/ld-powerpc/elfv2so.d: Update.
	* testsuite/ld-powerpc/tocopt.d: Update.
	* testsuite/ld-powerpc/tocopt.s: Update.
	* testsuite/ld-powerpc/tocopt5.d: Update.
	* testsuite/ld-powerpc/tocopt5.s: Update.
	* testsuite/ld-powerpc/tocopt7.d: Update.
	* testsuite/ld-powerpc/tocopt7.s: Update.
	* testsuite/ld-powerpc/tocopt8.d: Update.
	* testsuite/ld-powerpc/tocopt8.s: Update.