This commit adds support for the following instructions:
  vaddcuq, vadduqm, vaddecuq, vaddeuqm,
  vsubcuq, vsubuqm, vsubecuq, vsubeuqm,
  vbpermq and vgbbd.

The vgbbd instruction required a new Iop -- Iop_PwBitMtxXpose64x2.
All other instructions were emulated using existing Iops.

The completes adding the Power ISA 2.07 support.

Bugzilla 325816

git-svn-id: svn://svn.valgrind.org/vex/trunk@2790 8f6e269a-dfd6-0310-a8e1-e2731360e62c