Some targets still mess up the liveness information, but that isn't
verified after MRI->invalidateLiveness().
The verifier can still check other useful things like register classes
and CFG, so it should be enabled after all passes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153615 91177308-0d34-0410-b5e6-96231b3b80d8