Quick: Handle total high/low register overlap on arm/mips.

OpRegCopyWide() in arm and mips backends didn't handle the
total register overlap when the registers holding the source
and destination pairs are the same but in reverse order.

Bug: 21897012
Change-Id: Ia1f0005cbf5cc1c2d30899575dea21b3efa20ae6
2 files changed