SDL_mixer: update libxmp to latest master

From 877d0380ff214abc91fe1ac47370943e3866612f Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Thu, 24 Aug 2023 21:25:50 +0300
Subject: [PATCH] update libxmp to latest master

because the full library is under MIT license now.
---
 .gitmodules     | 2 +-
 external/libxmp | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.gitmodules b/.gitmodules
index 741c4d92..c517ffca 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -29,7 +29,7 @@
 [submodule "libxmp"]
 	path = external/libxmp
 	url = https://github.com/libsdl-org/libxmp.git
-	branch = 4.6.0-SDL
+	branch = 4.6.x-SDL
 [submodule "external/wavpack"]
 	path = external/wavpack
 	url = https://github.com/libsdl-org/wavpack.git
diff --git a/external/libxmp b/external/libxmp
index 85ee7857..30d6b428 160000
--- a/external/libxmp
+++ b/external/libxmp
@@ -1 +1 @@
-Subproject commit 85ee78575223009ecc51cd6961687b9e98d2a1e0
+Subproject commit 30d6b4284446b2dd6fc042cec9388321313ebb22