Revert r203883 (which was more of a bandaid) and fix the real underlying
issue in that the new MachineRegisterInfo bundle iterators didn't
dereference to the START of the bundle, while the old skipBundle()
method did.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203890 91177308-0d34-0410-b5e6-96231b3b80d8