[InstCombine][NFC] Add a ``break;`` statement.

This change is NFC because both the ``break;`` and the fall through end
up returning immediately. However, this helps clarify intent and also
ensures correctness in case more ``case`` blocks are added later.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239172 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed