Fix unsafe fallthrough at fbcode/fbpcf/scheduler/gate_keeper/BatchCom…

…positeGate.h:63 (#533)

Summary:
Pull Request resolved: #533

details in T179856888

**context**

LLVM has detected an implicit fallthrough near fbcode/fbpcf/scheduler/gate_keeper/BatchCompositeGate.h:63. Implicit fallthroughs have a very high bug rate, so we are making them a compiler error by default.

Reviewed By: ztlbells

Differential Revision: D54025656

fbshipit-source-id: 4a2c501c17063b2bb0a91489df169544b59ab75f

fbpcf/scheduler/gate_keeper/BatchCompositeGate.h

@@ -58,6 +58,7 @@ class BatchCompositeGate final : public ICompositeGate {
               engine.computeBatchFreeAND(
                   leftValues, wireKeeper_.getBatchBooleanValue(rights_[i])));
         }
+        break;
       }
 
       case GateType::NonFreeAnd: {