sdl2-compat: timer: Add notes on why SDL_GetTicks* APIs are implemented here.

From 85d3f84e914dcaee13efd6856b08cb7d03cc0bee Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Sun, 11 Dec 2022 23:58:18 -0500
Subject: [PATCH] timer: Add notes on why SDL_GetTicks* APIs are implemented
 here.

I'd like to do this for every API we add, but it might not be worth it.
---
 src/sdl2_compat.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/sdl2_compat.c b/src/sdl2_compat.c
index 3c90705..556586d 100644
--- a/src/sdl2_compat.c
+++ b/src/sdl2_compat.c
@@ -1528,12 +1528,14 @@ SDL_CreateRGBSurfaceWithFormatFrom(void *pixels, int width, int height, int dept
     return SDL3_CreateSurfaceFrom(pixels, width, height, pitch, format);
 }
 
+/* SDL_GetTicks is 64-bit in SDL3. Clamp it for SDL2. */
 DECLSPEC Uint32
 SDLCALL SDL_GetTicks(void)
 {
     return (Uint32)SDL3_GetTicks();
 }
 
+/* SDL_GetTicks64 is gone in SDL3 because SDL_GetTicks is 64-bit. */
 DECLSPEC Uint64
 SDLCALL SDL_GetTicks64(void)
 {