bfd:

bfd:
	* elf32-tic6x.c (elf32_tic6x_obj_attrs_handle_unknown): New.
	(elf32_tic6x_merge_attributes): Use
	_bfd_elf_merge_unknown_attribute_low and
	_bfd_elf_merge_unknown_attribute_list.
	(elf_backend_obj_attrs_handle_unknown): Define.

ld/testsuite:
	* ld-tic6x/attr-unknown-1.d, ld-tic6x/attr-unknown-1000-1.s,
	ld-tic6x/attr-unknown-1000-2.s, ld-tic6x/attr-unknown-1024-1.s,
	ld-tic6x/attr-unknown-2.d, ld-tic6x/attr-unknown-3.d,
	ld-tic6x/attr-unknown-4.d, ld-tic6x/attr-unknown-5.d,
	ld-tic6x/attr-unknown-54-1.s, ld-tic6x/attr-unknown-55-a.s,
	ld-tic6x/attr-unknown-6.d, ld-tic6x/attr-unknown-7.d,
	ld-tic6x/attr-unknown-71-a.s, ld-tic6x/attr-unknown-71-b.s: New
	tests.