Fix a miscompile in 186.crafty for Thumb2 that was exposed by Evan's

scheduling change in svn 115121.  The CriticalAntiDepBreaker had bad
liveness information.  It was calculating the KillIndices for one scheduling
region in a basic block, rescheduling that region so the KillIndices were
no longer valid, and then using those wrong KillIndices to make decisions
for the next scheduling region.  I've not been able to reduce a small
testcase for this.  Radar 8502534.

llvm-svn: 115400