bpo-38631: Avoid Py_FatalError() in _multibytecodec init (GH-17233)

If an exception is raised and PyInit__multibytecodec() returns NULL,
Python reports properly the exception to the user. There is no need
to crash Python with Py_FatalError().

Modules/cjkcodecs/multibytecodec.c

@@ -2085,7 +2085,6 @@ PyInit__multibytecodec(void)
     }
 
     if (PyErr_Occurred()) {
-        Py_FatalError("can't initialize the _multibytecodec module");
         Py_DECREF(m);
         m = NULL;
     }