[nostalgia/core] Add ticksMs() function

src/nostalgia/core/sdl/core.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 - 2019 gtalent2@gmail.com
+ * Copyright 2016 - 2020 gary@drinkingtea.net
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -41,4 +41,8 @@ ox::Error run(Context *ctx) {
 	return OxError(0);
 }
 
+uint64_t ticksMs() {
+	return SDL_GetTicks();;
+}
+
 }