Fix subreg value numbers in handleMoveUp

Fix subreg value numbers in handleMoveUp

The problem can occur in presence of subregs. If we are swapping two
instructions defining different subregs of the same register we will
get a new liveout from a block. We need to preserve value number for
block's liveout for successor block's livein to match.

Differential Revision: https://reviews.llvm.org/D30558

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297534 91177308-0d34-0410-b5e6-96231b3b80d8