[GOLD] PowerPC64 inline plt sequences

[GOLD] PowerPC64 inline plt sequences

The fixes gold failures to handle inline PLT sequences properly.
PowerPC gold was always turning these back into direct calls due to
gsym->use_plt_offset() returning false.  This is fixed for dynamic
linking by correcting get_reference_flags, and for static linking by
overriding use_plt_offset() in relocate().  The rest of the patch
revolves around needing to create PLT entries for inline PLT calls
when statically linking (for gcc -mlongcall).  The lplt section
handled that for local symbols, now it does globals too.

	* powerpc.cc (Target_powerpc::plt_off): Return proper section
	for static link.
	(Target_powerpc::symval_for_branch): Make public.
	(Target_powerpc::make_lplt_section): Add Symbol_table* param.
	Adjust all calls.
	(Target_powerpc::make_local_plt_entry): Likewise.
	(Target_powerpc::make_local_plt_entry): New variant for global syms.
	(Powerpc_relobj::do_relocate_sections): Don't write lplt contents.
	(Output_data_plt_powerpc::do_write): Write lplt contents here.
	(Output_data_plt_powerpc::Output_data_plt_powerpc): Save
	symbol table pointer.  Adjust all uses.
	(Output_data_plt_powerpc::add_entry): Add stash parameter.  Don't
	do dynamic reloc handling when no reloc section.  Save symbol
	for local plt entries.
	(Output_data_plt_powerpc::add_local_entry): Save symbol.
	(Output_data_plt_powerpc::Local_plt_ent): New class.
	(Output_data_plt_powerpc::sym_ents_): New vector.
	(Target_powerpc::Scan::get_reference_flags): Return
	FUNCTION_CALL|RELATIVE_REF for inline plt relocs.
	(Target_powerpc::Scan::global): Make entries in lplt for inline
	plt call relocation symbols.
	(Target_powerpc::Relocate::relocate): Rename has_plt_offset to
	use_plt_offset.  Set use_plt_offset for inline plt relocs.