Linker foreign output format support for PowerPC64 ELFv2

Linker foreign output format support for PowerPC64 ELFv2

Makes the ld srec tests pass.  Uses a horrible scan through symbols to
find ELF fields for symbol definitions, but the generic linker doesn't
offer anything better.  Might be slow.  Anyway, sane people will link
to ELF output then objcopy to convert formats.

	* elf64-ppc.c (abiversion, set_abiversion): Move earlier.
	(ppc64_elf_branch_reloc): Adjust addend for ELFv2 local offset.
	(ppc64_elf_set_toc): Set ".TOC." symbol value when using
	generic linker.
	(ppc64_elf_relocate_section): Disable ELFv2 function entry
	optimisation when --traditional-format.