RegisterPressure: Add PressureDiff::dump()

Also display the pressure diff in the case of a
getMaxUpwardPressureDelta() verify failure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241759 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed