sdl12-compat: Make a gigantic stack allocation static.

SDL Commits
1 
From 327226f6e6d52626998fcfc0eed22ebd3dd4fc8e Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Mon, 7 Jun 2021 15:50:53 -0400
Subject: [PATCH] Make a gigantic stack allocation static.

This is only safe because we only decode one mp3 at a time, but cleaning this
up more properly would be good.

Should prevent MSVC from inserting a call to _chkstk here.
---
 src/dr_mp3.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/dr_mp3.h b/src/dr_mp3.h
index e28f318..0cbeab1 100644
--- a/src/dr_mp3.h
+++ b/src/dr_mp3.h
@@ -2218,7 +2218,7 @@ DRMP3_API int drmp3dec_decode_frame(drmp3dec *dec, const drmp3_uint8 *mp3, int m
     int i = 0, igr, frame_size = 0, success = 1;
     const drmp3_uint8 *hdr;
     drmp3_bs bs_frame[1];
-    drmp3dec_scratch scratch;
+    static drmp3dec_scratch scratch;
 
     if (mp3_bytes > 4 && dec->header[0] == 0xff && drmp3_hdr_compare(dec->header, mp3))
     {