SDL_mixer: fix a -Wunused-but-set-variable warning.

SDL Commits
1 
From 1e13c1b345f1dc1f070a3cba8271b24d5328047c Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Tue, 11 Aug 2026 17:01:02 +0300
Subject: [PATCH] fix a -Wunused-but-set-variable warning.

---
 src/codecs/timidity/timidity.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/codecs/timidity/timidity.c b/src/codecs/timidity/timidity.c
index d5d4e1eb..57903e21 100644
--- a/src/codecs/timidity/timidity.c
+++ b/src/codecs/timidity/timidity.c
@@ -421,6 +421,8 @@ static int read_config_file(const char *name, int rcf_count)
     }
   }
 
+  (void) line;
+
   r = 0; /* we're good. */
 fail:
   SDL_RWclose(rw);