* elf32.c (elf_object_p): Use ELF_ARCH stored in xvec to match

	* elf32.c (elf_object_p):  Use ELF_ARCH stored in xvec to match
	against machine architecture stored in the ELF header, to resolve
	ambiguities.
	* elf32.c (bfd_section_from_shdr):  Bfd_make_section can return
	NULL, so only use results when non-NULL.
	* targets.c (elf32_m68k_vec, elf32_i860_vec):  Add extern decls
	and add to vector of targets.