SWORD25: Fix bug #6981: High CPU usage on one core

The game loop is implemented in Lua, and there are no delays.
Now we wait 10ms on each event pulling, as we always do.

engines/sword25/kernel/kernel_script.cpp

@@ -257,6 +257,7 @@ static int processMessages(lua_State *L) {
 	// to the closeWanted() opcode; see also the TODO comment in there.
 
 	lua_pushbooleancpp(L, !Engine::shouldQuit());
+	g_system->delayMillis(10);
 
 	return 1;
 }