SDL_mixer: Revert accidental wavpack submodule revert

From 58bd16894d9030d751dcd8afeb967f2e558601ee Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Tue, 19 Sep 2023 22:14:07 +0200
Subject: [PATCH] Revert accidental wavpack submodule revert

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

diff --git a/external/wavpack b/external/wavpack
index 4ca31b02..7578f99b 160000
--- a/external/wavpack
+++ b/external/wavpack
@@ -1 +1 @@
-Subproject commit 4ca31b02865e94858c489c9a86a5f5c84843fc79
+Subproject commit 7578f99b405a74bfc3f4cdd904e22139520b7f12