SDL: testaudio: Patched to compile.

From ad1313e7512db5a47dc94a6662f7245b9bc5acb5 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Thu, 7 Sep 2023 16:03:49 -0400
Subject: [PATCH] testaudio: Patched to compile.

(this was a piece of PR #8213 that accidentally creeped into main.)
---
 test/testaudio.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/test/testaudio.c b/test/testaudio.c
index 92388cf3c532..31659635bc6a 100644
--- a/test/testaudio.c
+++ b/test/testaudio.c
@@ -206,8 +206,6 @@ static Thing *UpdateMouseOver(const float x, const float y)
         SetTitleBar("%s", thing->titlebar);
     }
 
-    mouseover_thing = thing;
-
     return thing;
 }