Silence unused warnings

include/swift/Driver/ExperimentalDependencyDriverGraph.h

@@ -223,6 +223,7 @@ class ModuleDepGraph {
     ModuleDepGraphNode *nodeActuallyErased = nodeMap.findAndErase(
         nodeToErase->getSwiftDeps().getValueOr(std::string()),
         nodeToErase->getKey());
+    (void)nodeActuallyErased;
     assert(
         nodeToErase == nodeActuallyErased ||
         mapCorruption("Node found from key must be same as node holding key."));