* Modify the instrumenter to use the new primops introduced in

* Modify the instrumenter to use the new primops introduced in
  vex rev 1144.

* Observe that mkLazy2 generates IR which often turns into
  long and slow code sequences in the back end, primarily because
  PCast operations are expensive.  Add a couple of special
  cases which give noticably better performance when handling
  FP-intensive code on x86.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@3572