qom: Make object_resolve_path_component() path argument const

A usage with a hardcoded partial path such as

  object_resolve_path_component(obj, "foo")

is totally valid but currently leads to a compilation error. Fix this.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

include/qom/object.h

@@ -900,7 +900,7 @@ Object *object_resolve_path_type(const char *path, const char *typename,
  *
  * Returns: The resolved object or NULL on path lookup failure.
  */
-Object *object_resolve_path_component(Object *parent, gchar *part);
+Object *object_resolve_path_component(Object *parent, const gchar *part);
 
 /**
  * object_property_add_child:

qom/object.c

@@ -1017,7 +1017,7 @@ gchar *object_get_canonical_path(Object *obj)
     return newpath;
 }
 
-Object *object_resolve_path_component(Object *parent, gchar *part)
+Object *object_resolve_path_component(Object *parent, const gchar *part)
 {
     ObjectProperty *prop = object_property_find(parent, part, NULL);
     if (prop == NULL) {