TableGen infers unmodeled side effects on instructions without a
pattern. Fix some instruction definitions where that was overlooked.
Also raise an error if a rematerializable instruction has unmodeled side
effects. That doen't make any sense.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141929 91177308-0d34-0410-b5e6-96231b3b80d8