bpo-36356: pymain_exit_error() only call pymain_free() for exit (GH-12968)

Add _Py_INIT_HAS_EXITCODE() macro.
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index ae2d0bf..d93fe06 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -2172,7 +2172,7 @@
 void _Py_NO_RETURN
 _Py_ExitInitError(_PyInitError err)
 {
-    if (err.exitcode >= 0) {
+    if (_Py_INIT_HAS_EXITCODE(err)) {
         exit(err.exitcode);
     }
     else {