Improve handling of EnforceSmallerThan. Remove all types that are smaller from the larger set not just the smallest type from the smaller set. Ensure 'smaller' vectors have the same or fewer total bits. Similar for 'larger' vectors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200287 91177308-0d34-0410-b5e6-96231b3b80d8