Select and emit insns for
Iop_ZeroHI64ofV128 Iop_Max8Sx16 Iop_Min8Sx16


git-svn-id: svn://svn.valgrind.org/vex/trunk@2828 8f6e269a-dfd6-0310-a8e1-e2731360e62c
Remove redundant FMOV (vector, immediate) case.
Minor comment fixes.
Fix bugs in {U,S}{MIN,MAX}V, {U,S}{MIN,MAX}, {S,U}SSHL


git-svn-id: svn://svn.valgrind.org/vex/trunk@2829 8f6e269a-dfd6-0310-a8e1-e2731360e62c