SDL_mixer: decoder_sinewave.c: include stddef.h for ptrdiff_t

SDL Commits
1 
From 8f6de51e559d21890474eb3be6275376a892e43e Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Thu, 15 Jan 2026 01:15:10 +0300
Subject: [PATCH] decoder_sinewave.c: include stddef.h for ptrdiff_t

---
 src/decoder_sinewave.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/decoder_sinewave.c b/src/decoder_sinewave.c
index 2a5f58f9..5f4c6af4 100644
--- a/src/decoder_sinewave.c
+++ b/src/decoder_sinewave.c
@@ -28,6 +28,7 @@
 //   - decode just needs to see if one of the buffers is complete and push it again.
 //   - clear/push a subset when seeking.
 
+#include <stddef.h>
 #include "SDL_mixer_internal.h"
 
 typedef struct SINEWAVE_AudioData