sdl12-compat: Fixed a SDL_GetMouseState that should be SDL20_GetMouseState.

SDL Commits
1 
From 19823493da98acb0e938468daacd40bfdb974b0c Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Tue, 1 Jun 2021 16:07:44 -0400
Subject: [PATCH] Fixed a SDL_GetMouseState that should be SDL20_GetMouseState.

---
 src/SDL12_compat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 623155e..6b37825 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -4377,7 +4377,7 @@ UpdateRelativeMouseMode(void)
             if (MouseInputIsRelative) {
                 /* reset position, we'll have to track it ourselves in SDL_MOUSEMOTION events, since 1.2
                  *  would give you window coordinates, even in relative mode. */
-                SDL_GetMouseState(&MousePosition.x, &MousePosition.y);
+                SDL20_GetMouseState(&MousePosition.x, &MousePosition.y);
             }
             SDL20_SetRelativeMouseMode(MouseInputIsRelative);
         }