Don't sort ld -r relocs for mips

Don't sort ld -r relocs for mips

HI16/LO16 are deliberately put adjacent, which might mean relocs are
then not sorted by r_offset.  See tc-mips.c:mips_frob_file.  Don't undo
the HI16/LO16 sorting.

	PR 17666
	* elf-bfd.h (struct elf_backend_data): Add sort_relocs_p.
	* elfxx-target.h (elf_backend_sort_relocs_p): Define.
	(elfNN_bed): Init new field.
	* elflink.c (elf_link_adjust_relocs): Conditionally sort.
	(bfd_elf_final_link): Control sorting of relocs.
	* elfxx-mips.c (_bfd_mips_elf_sort_relocs_p): New function.
	* elfxx-mips.h (_bfd_mips_elf_sort_relocs_p): Declare.
	* elf32-mips.c (elf_backend_sort_relocs_p): Define.
	* elf64-mips.c (elf_backend_sort_relocs_p): Define.