PR ld/10406

	PR ld/10406
	* elf32-ppc.c (ppc_elf_howto_raw): Make R_PPC_EMB_SDAI16 and
	R_PPC_EMB_SDA2I16 complain_overflow_signed.
	(create_sdata_sym): Pass info rather than htab.
	Update all callers.  Ensure symbols are hidden.
	(ppc_elf_check_relocs): Allow SDAREL16 when shared.
	(ppc_elf_size_dynamic_sections): When shared, equate _SDA_BASE_ to
	_GLOBAL_OFFSET_TABLE_.
	(elf_finish_pointer_linker_section): Don't assume that sdata base
	symbol is always at 0x8000 offset.  Don't subtract the addend here.
	(is_static_defined): New function.
	(ppc_elf_relocate_section): Verify symbol base used in SDA relocs
	is statically defined.  Clear addend for EMB_SDAI16 and EMB_SDA2I16
	relocs.  Downgrade error on unexpected section for EMB_SDA2REL
	reloc symbols to a warning.