handle non-cmovcc predication properly

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on October 27, 2014 14:55:45_

Today DrMem handles OP_cmovcc and OP_fcmovcc on both the fastpath and
slowpath.

This issue covers handling OP_bsf, OP_bsr, OP__maskmov_, and other
predication properly, and possibly adding fastpath handling for it as well.

Xref DRi#269.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=1649_