SDL_mixer: update vendored wavpack.

From 2154720fa7a87394841a0599545e53882490149b Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Wed, 11 Oct 2023 14:21:40 +0300
Subject: [PATCH] update vendored wavpack.

---
 external/wavpack | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/external/wavpack b/external/wavpack
index f6236857..11a91b56 160000
--- a/external/wavpack
+++ b/external/wavpack
@@ -1 +1 @@
-Subproject commit f62368577ffad682eca0c0262adefc93ebdad744
+Subproject commit 11a91b5622dab59ba5ce2f9aded90d5b4a9dc299