Fix "variable unused" warning in Metadata.cpp in non-assert build

Author: kubamracek

stdlib/public/runtime/Metadata.cpp

@@ -2831,9 +2831,8 @@ allocateWitnessTable(GenericWitnessTable *genericTable,
 
   // The number of mandatory requirements, i.e. requirements lacking
   // default implementations.
-  size_t numMandatoryRequirements =
-    protocol->NumMandatoryRequirements + WitnessTableFirstRequirementOffset;
-  assert(numPatternWitnesses >= numMandatoryRequirements);
+  assert(numPatternWitnesses >= protocol->NumMandatoryRequirements +
+                                    WitnessTableFirstRequirementOffset);
 
   // The total number of requirements.
   size_t numRequirements =