PowerPC64 GOT reloc optimisation

PowerPC64 GOT reloc optimisation

When the symbol referenced by a GOT reloc is an ifunc, we can't
optimise away the GOT indirection.  Well, we can, but only if a global
entry stub is created with the ifunc symbol redefined to the stub.
But that results in slower code and an indirection via the PLT so
there isn't much to like about that solution.

	* elf64-ppc.c (ppc64_elf_edit_toc): Exclude ifunc from GOT
	optimisation.
	(ppc64_elf_relocate_section): Likewise.