arm64: implement: sabal uabal sabdl uabdl saddl uaddl ssubl usubl
smlal umlal smlsl umlsl smull umull


git-svn-id: svn://svn.valgrind.org/vex/trunk@2893 8f6e269a-dfd6-0310-a8e1-e2731360e62c
arm64: change the representation of FPSR.QC so that it can be
used efficiently to record SIMD saturation, and remove support
for all other bits of FPSR, since we don't model them anyway.


git-svn-id: svn://svn.valgrind.org/vex/trunk@2894 8f6e269a-dfd6-0310-a8e1-e2731360e62c