PowerPC: downgrade FP mismatch error for shared libraries to a warning

	PR 25882
bfd/
	* elf32-ppc.c (_bfd_elf_ppc_merge_fp_attributes): Don't init FP
	attributes from shared libraries, and do not return an error if
	they don't match.
gold/
	* powerpc.cc (merge_object_attributes): Replace name param with
	obj param.  Update callers.  Don't init FP attributes from shared
	libraries, and do not emit an error if they don't match.