Apply two changes, systematically:

(1) Use PyErr_NewException("module.class", NULL, NULL) to create the
    exception object.

(2) Remove all calls to Py_FatalError(); instead, return or
    ignore the errors -- the import code now checks PyErr_Occurred()
    after calling a module's init function, so it's no longer a
    fatal error for the initialization to fail.

Also did some small cleanups, e.g. removed unnecessary test for
"already initialized" from initfpectl(), and unified
initposix()/initnt().

I haven't checked this very thoroughly, so while the changes are
pretty trivial -- beware of untested code!
diff --git a/Modules/stdwinmodule.c b/Modules/stdwinmodule.c
index a67bc33..0403138 100644
--- a/Modules/stdwinmodule.c
+++ b/Modules/stdwinmodule.c
@@ -2651,13 +2651,11 @@
 	d = PyModule_GetDict(m);
 	
 	/* Initialize stdwin.error exception */
-	StdwinError = PyString_FromString("stdwin.error");
+	StdwinError = PyErr_NewException("stdwin.error", NULL, NULL);
 	if (StdwinError == NULL ||
 	    PyDict_SetItemString(d, "error", StdwinError) != 0)
-		Py_FatalError("can't define stdwin.error");
+		return;
 #ifdef WITH_THREAD
 	StdwinLock = allocate_lock();
-	if (StdwinLock == NULL)
-		Py_FatalError("can't allocate stdwin lock");
 #endif
 }