Add ELFv2 .localentry support.

Add ELFv2 .localentry support.

This defines the ELF symbol st_other field used to encode the number
of instructions between a function "global entry" and its "local entry",
and adds support related to the local entry offset.

include/elf/
	* ppc64.h (STO_PPC64_LOCAL_BIT, STO_PPC64_LOCAL_MASK): Define.
	(ppc64_decode_local_entry, ppc64_encode_local_entry): New functions.
	(PPC64_LOCAL_ENTRY_OFFSET, PPC64_SET_LOCAL_ENTRY_OFFSET): Define.
bfd/
	* elf64-ppc.c (struct ppc_stub_hash_entry): Add "other".
	(stub_hash_newfunc): Init new ppc_stub_hash_entry field, and one
	we forgot, "plt_ent".
	(ppc64_elf_add_symbol_hook): Check ELFv1 objects don't have
	st_other bits only valid in ELFv2.
	(ppc64_elf_merge_symbol_attribute): New function.
	(ppc_type_of_stub): Add local_off param to test branch range.
	(ppc_build_one_stub): Adjust destinations for ELFv2 locals.
	(ppc_size_one_stub, toc_adjusting_stub_needed): Similarly.
	(ppc64_elf_size_stubs): Pass local_off to ppc_type_of_stub.
	Set "other" field.
	(ppc64_elf_relocate_section): Adjust destination for ELFv2 local
	calls.
gas/
	* config/tc-ppc.c (md_pseudo_table): Add .localentry.
	(ppc_elf_localentry): New function.
	(ppc_force_relocation): Force relocs on all branches to localenty
	symbols.
	(ppc_fix_adjustable): Don't reduce such symbols to section+offset.
binutils/
	* readelf.c (get_ppc64_symbol_other): New function.
	(get_symbol_other): Use it for EM_PPC64.