Make sure that vlc.gettext.N_() returns the first argument.

modules/misc/lua/libs/gettext.c

@@ -52,7 +52,7 @@ static int vlclua_gettext( lua_State *L )
 
 static int vlclua_gettext_noop( lua_State *L )
 {
-    (void)L;
+    lua_settop( L, 1 );
     return 1;
 }