MachineSink: make shouldSink a TII target hook

Some targets may disagree on what they want sunk or not sunk,
so make this a target hook instead of hardcoded.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264799 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed