Support PLT16 relocs against local symbols

Support PLT16 relocs against local symbols

Necessary if gcc is to use PLT16 relocs to implement -mlongcall, and
there isn't a good technical reason why local symbols should be
excluded from PLT16 support.  Non-ifunc local symbol PLT entries go in
a separate section to other PLT entries.  In a fixed position
executable they won't need to be relocated, and in a PIE or shared
library I chose to not implement lazy relocation.

bfd/
	* elf64-ppc.c (LOCAL_PLT_ENTRY_SIZE): Define.
	(struct ppc_stub_hash_entry): Add symtype field.
	(PLT_KEEP): Define.
	(struct ppc_link_hash_table): Add pltlocal and relpltlocal.
	(create_linkage_sections): Create pltlocal and relpltlocal.
	(ppc64_elf_check_relocs): Allow PLT relocs on local symbols.
	Set PLT_KEEP.
	(ppc64_elf_adjust_dynamic_symbol): Keep PLT entries for inline calls.
	(allocate_dynrelocs): Allocate pltlocal and relpltlocal.
	(ppc64_elf_size_dynamic_sections): Size pltlocal and relpltlocal.
	Keep PLT entries for inline calls against locals.
	(ppc_build_one_stub): Use pltlocal as appropriate.
	(ppc_size_one_stub): Likewise.
	(ppc64_elf_size_stubs): Set symtype.
	(build_global_entry_stubs_and_plt): Init pltlocal and write
	relpltlocal for globals.
	(write_plt_relocs_for_local_syms): Likewise for local syms.
	(ppc64_elf_relocate_section): Support PLT for local syms.
	* elf32-ppc.c (PLT_KEEP): Define.
	(struct ppc_elf_link_hash_table): Add pltlocal and relpltlocal.
	(ppc_elf_create_glink): Create pltlocal and relpltlocal.
	(ppc_elf_check_relocs): Allow PLT relocs on local symbols.
	Set PLT_KEEP.  Adjust update_local_sym_info call.
	(ppc_elf_adjust_dynamic_symbol): Keep PLT entries for inline calls.
	(allocate_dynrelocs): Allocate pltlocal and relpltlocal.
	(ppc_elf_size_dynamic_sections): Size pltlocal and relpltlocal.
	(ppc_elf_relocate_section): Support PLT16 relocs for local syms.
	(write_global_sym_plt): Init pltlocal and write relpltlocal.
	(ppc_finish_symbols): Likewise for locals.
ld/
	* emulparams/elf32ppc.sh (OTHER_RELRO_SECTIONS_2): Add .branch_lt.
	(OTHER_GOT_RELOC_SECTIONS): Add .rela.branch_lt.
	* testsuite/ld-powerpc/elfv2so.d: Update for symbol/stub reordering.
	* testsuite/ld-powerpc/relbrlt.d: Likewise.
	* testsuite/ld-powerpc/relbrlt.s: Likewise.
	* testsuite/ld-powerpc/tlsso.r: Likewise.
	* testsuite/ld-powerpc/tlstocso.r: Likewise.
gold/
	* powerpc.cc (Target_powerpc::lplt_): New variable.
	(Target_powerpc::lplt_section): Associated accessor.
	(Target_powerpc::plt_off): Handle local non-ifunc symbols.
	(Target_powerpc::make_lplt_section): New function.
	(Target_powerpc::make_local_plt_entry): New function.
	(Powerpc_relobj::do_relocate_sections): Write out lplt.
	(Output_data_plt_powerpc::first_plt_entry_offset): Zero for lplt.
	(Output_data_plt_powerpc::add_local_entry): New function.
	(Output_data_plt_powerpc::do_write): Ignore lplt.
	(Target_powerpc::make_iplt_section): Make lplt first.
	(Target_powerpc::make_brlt_section): Make .branch_lt relro.
	(Target_powerpc::Scan::local): Handle PLT16 relocs.