Revert r153516: "Invalidate liveness in Thumb2ITBlockPass."

Revert r153519: "ARMLoadStoreOptimizer invalidates register liveness."

These patches caused miscompilations in povray by turning off branch
folding's updating of live-in lists.

It turns out the the late scheduler depends on the live-in lists, even
if it doesn't need correct kill flags.

<rdar://problem/11139228>

llvm-svn: 153593