xml/export/v1/memory: change a variable to signed int

weight() returns a signed int, so assert is better if we stay signed.

CID#1445010

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

hwloc/topology-xml.c

@@ -2365,7 +2365,7 @@ static unsigned
 hwloc__xml_v1export_object_list_numanodes(hwloc_obj_t obj, hwloc_obj_t *first_p, hwloc_obj_t **nodes_p)
 {
   hwloc_obj_t *nodes, cur;
-  unsigned nr;
+  int nr;
 
   if (!obj->memory_first_child) {
     *first_p = NULL;