Perform system allocator's mutex unlock anyways

src/dmmlib.c

@@ -143,6 +143,7 @@ void * malloc(size_t size) {
             pthread_mutex_unlock(&new_raw_block->mutex);
 #endif /* HAVE_LOCKS */
         }
+        pthread_mutex_unlock(&systemallocator.creation_mutex);
     }
     
     return ptr;