SDL_mixer: fixed several -Wzero-as-null-pointer-constant warnings from gcc-15

SDL Commits
1 
From 3071e49006f9183f5886025276bf5743b1854b0d Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Mon, 17 Nov 2025 22:25:56 +0300
Subject: [PATCH] fixed several -Wzero-as-null-pointer-constant warnings from
 gcc-15

---
 src/timidity/options.h  | 2 +-
 src/timidity/timidity.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/timidity/options.h b/src/timidity/options.h
index 025dfd978..045295024 100644
--- a/src/timidity/options.h
+++ b/src/timidity/options.h
@@ -12,7 +12,7 @@
 /* When a patch file can't be opened, one of these extensions is
    appended to the filename and the open is tried again.
  */
-#define PATCH_EXT_LIST { ".pat", 0 }
+#define PATCH_EXT_LIST { ".pat", NULL }
 
 /* Acoustic Grand Piano seems to be the usual default instrument. */
 #define DEFAULT_PROGRAM 0
diff --git a/src/timidity/timidity.c b/src/timidity/timidity.c
index 8338624fb..563bba905 100644
--- a/src/timidity/timidity.c
+++ b/src/timidity/timidity.c
@@ -96,7 +96,7 @@ static int read_config_file(const char *name, int rcf_count)
         /* Originally the TiMidity++ extensions were prefixed like this */
     if (SDL_strcmp(w[0], "#extension") == 0)
     {
-        w[0]=SDL_strtok_r(0, " \t\240", &endp);
+        w[0]=SDL_strtok_r(NULL, " \t\240", &endp);
         if (!w[0]) continue;
     }