Fix resource leak in parser, free node ptr

CID 1028068 (#1 of 1): Resource leak (RESOURCE_LEAK)
leaked_storage: Variable n going out of scope leaks the storage it points to.

Parser/pgenmain.c

@@ -113,6 +113,7 @@ getgrammar(char *filename)
         Py_Exit(1);
     }
     g = pgen(n);
+    PyNode_Free(n);
     if (g == NULL) {
         printf("Bad grammar.\n");
         Py_Exit(1);