Don't crash in the odd event you have no modules loaded

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@12430 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch_loadable_module.c

@@ -1267,6 +1267,10 @@ SWITCH_DECLARE(void) switch_loadable_module_shutdown(void)
 	void *val;
 	switch_loadable_module_t *module;
 	
+	if (!loadable_modules.module_hash) {
+		return;
+	}
+
 	for (hi = switch_hash_first(NULL, loadable_modules.module_hash); hi; hi = switch_hash_next(hi)) {
 		switch_hash_this(hi, NULL, NULL, &val);
 		module = (switch_loadable_module_t *) val;