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!

Modules/xxmodule.c

@@ -231,10 +231,6 @@ initxx()
 
 	/* Add some symbolic constants to the module */
 	d = PyModule_GetDict(m);
-	ErrorObject = PyString_FromString("xx.error");
+	ErrorObject = PyErr_NewException("xx.error", NULL, NULL);
 	PyDict_SetItemString(d, "error", ErrorObject);
-
-	/* Check for errors */
-	if (PyErr_Occurred())
-		Py_FatalError("can't initialize module xx");
 }