gas/

gas/
* config/tc-mips.c (append_insn): Properly detect variant frags
that preclude swapping of relaxed branches.  Correctly swap
instructions between frags when dealing with relaxed branches.

gas/testsuite/
* gas/mips/relax-swap1-mips1.d: New test for branch relaxation
with swapping for MIPS1.
* gas/mips/relax-swap1-mips2.d: New test for branch relaxation
with swapping for MIPS2.
* gas/mips/relax-swap1.l: Stderr output for the new tests.
* gas/mips/relax-swap1.s: Source for the new tests.
* gas/mips/relax-swap2.d: New test for branch likely relaxation
with swapping.
* gas/mips/relax-swap2.l: Stderr output for the new test.
* gas/mips/relax-swap2.s: Source for the new test.
* gas/mips/mips.exp: Run the new tests.