[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

lib/Transforms/InstCombine/InstCombineCompares.cpp

@@ -2195,6 +2195,7 @@ bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS,
       if (WillNotOverflowSignedMul(LHS, RHS, OrigI))
         return SetResult(Builder->CreateNSWMul(LHS, RHS), Builder->getFalse(),
                          true);
+    break;
   }
 
   return false;