BUG: Update control flow edges in lock-step execution pass,.

git-svn-id: http://gpuocelot.googlecode.com/svn/trunk@2225 ec522b64-56cd-11de-8d7d-01d876f1962d
BUG: Update mask reset operation got the begin/end reversed.

git-svn-id: http://gpuocelot.googlecode.com/svn/trunk@2226 ec522b64-56cd-11de-8d7d-01d876f1962d