front end:

front end:
 - implemented insns: mfvscr, mtvscr, vand, vor, vxor
 - fixed default vscr: enable non-java mode

back end:
 - implemented enough to satisfy the front end: V128to32, 32UtoV128, not, and, or, xor
 - fixed conversions to/from v128 to use quad-word-aligned stack addressing for their vector load/stores

git-svn-id: svn://svn.valgrind.org/vex/trunk@1386