* elf-attrs.c (_bfd_elf_merge_unknown_attribute_low,

	* elf-attrs.c (_bfd_elf_merge_unknown_attribute_low,
	_bfd_elf_merge_unknown_attribute_list): New.
	* elf-bfd.h (struct elf_backend_data): Add
	obj_attrs_handle_unknown.
	(_bfd_elf_merge_unknown_attribute_low,
	_bfd_elf_merge_unknown_attribute_list): Declare.
	* elf32-arm.c (elf32_arm_obj_attrs_handle_unknown): New.  Split
	out from elf32_arm_merge_eabi_attributes.
	(elf32_arm_merge_eabi_attributes): Use
	_bfd_elf_merge_unknown_attribute_low and
	_bfd_elf_merge_unknown_attribute_list.
	(elf_backend_obj_attrs_handle_unknown): Define.
	* elfxx-target.h (elf_backend_obj_attrs_handle_unknown): Define.
	(elfNN_bed): Update initializer.