PowerPC64 ld --no-power10-stubs

Needed for libraries that use ifuncs or other means to support
cpu-optimized versions of functions, some power10, some not, and those
functions make calls using linkage stubs.

bfd/
	* elf64-ppc.h (struct ppc64_elf_params): Add power10_stubs.
	* elf64-ppc.c (struct ppc_link_hash_table): Delete
	power10_stubs.
	(ppc64_elf_check_relocs): Adjust setting of power10_stubs.
	(plt_stub_size, ppc_build_one_stub, ppc_size_one_stub): Adjust
	uses of power10_stubs.
ld/
	* emultempl/ppc64elf.em (params): Init new field.
	(enum ppc64_opt): Add OPTION_POWER10_STUBS and OPTION_NO_POWER10_STUBS.
	(PARSE_AND_LIST_LONGOPTS): Support --power10-stubs and
	--no-power10-stubs.
	(PARSE_AND_LIST_OPTIONS, PARSE_AND_LIST_ARGS_CASES): Likewise.
	* testsuite/ld-powerpc/callstub-3.d: New test.
	* testsuite/ld-powerpc/powerpc.exp: Run it.