mips64: add support for Cavium BBIT032 and BBIT132

This patch adds support for two Cavium specific instructions:
- BBIT032 (Branch on Bit Clear Plus 32), and
- BBIT132 (Branch on Bit Set Plus 32).

Missing support reported in BZ #339288.

Patch by Maran Pakkirisamy.


git-svn-id: svn://svn.valgrind.org/vex@3028 8f6e269a-dfd6-0310-a8e1-e2731360e62c