Fix internal errors like:
ld: BFD (GNU Binutils) 2.26.51.20160526 internal error, aborting at .../bfd/elfxx-mips.c:10278 in _bfd_mips_elf_relocate_section
ld: Please report this bug.
triggered by the `bfd_reloc_outofrange' condition on branch relocations.
bfd/
* elfxx-mips.c (b_reloc_p): New function.
(_bfd_mips_elf_relocate_section) <bfd_reloc_outofrange>: Handle
branch relocations.
ld/
* testsuite/ld-mips-elf/unaligned-branch.d: New test.
* testsuite/ld-mips-elf/unaligned-branch.s: New test source.
* testsuite/ld-mips-elf/unaligned-text.s: New test source.
* testsuite/ld-mips-elf/mips-elf.exp: Run the new test.
