add conditional to suppress unused variable warning in Release builds

indra/newview/llmaterialmgr.cpp

@@ -384,7 +384,9 @@ void LLMaterialMgr::onPutResponse(bool success, const LLSD& content)
 
 		for (LLSD::array_const_iterator faceIter = response_data.beginArray(); faceIter != response_data.endArray(); ++faceIter)
 		{
-			const LLSD& face_data = *faceIter;
+#           ifndef LL_RELEASE_FOR_DOWNLOAD
+			const LLSD& face_data = *faceIter; // conditional to avoid unused variable warning
+#           endif
 			llassert(face_data.isMap());
 
 			llassert(face_data.has(MATERIALS_CAP_OBJECT_ID_FIELD));