dispatcher: silence warning about sub-directories in dispatcher directory

Especially now that we have the 'pre-up.d/' and 'pre-down.d/' directories,
silently skip over any sub directories inside the dispatcher directory.

Fixes warning:
  nm-dispatcher: Cannot execute '/etc/NetworkManager/dispatcher.d/pre-up.d': not a regular file.

Signed-off-by: Thomas Haller <thaller@redhat.com>

callouts/nm-dispatcher.c

@@ -454,6 +454,8 @@ find_scripts (const char *str_action)
 		err = stat (path, &st);
 		if (err)
 			g_warning ("Failed to stat '%s': %d", path, err);
+		else if (S_ISDIR (st.st_mode))
+			; /* silently skip. */
 		else if (!check_permissions (&st, &err_msg))
 			g_warning ("Cannot execute '%s': %s", path, err_msg);
 		else {