Add algebraic simplifications for Iop_And64 (same as for Iop_And32).
Remove isOnesU32 which is no longer needed.


git-svn-id: svn://svn.valgrind.org/vex/trunk@2746 8f6e269a-dfd6-0310-a8e1-e2731360e62c
Add an optimisation for Iop_Left64.


git-svn-id: svn://svn.valgrind.org/vex/trunk@2747 8f6e269a-dfd6-0310-a8e1-e2731360e62c