Use correct conversion format for python strpool id's

- We need an unsigned int, not unsigned long. Funnily enough "k"
  worked with gcc -O0 and -O1 but blows up when built with -O2.

python/rpmstrpool-py.c

@@ -40,7 +40,7 @@ static PyObject *strpool_id2str(rpmstrPoolObject *s, PyObject *item)
     PyObject *ret = NULL;
     rpmsid id = 0;
 
-    if (PyArg_Parse(item, "k", &id)) {
+    if (PyArg_Parse(item, "I", &id)) {
 	const char *str = rpmstrPoolStr(s->pool, id);
 
 	if (str)