SDL_mixer: upgrade vendored libxmp to latest 4.6.3 release (bb140)

From bb1406a062f061a3c9d781a5c14317d38daabe15 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Tue, 13 May 2025 23:10:10 +0300
Subject: [PATCH] upgrade vendored libxmp to latest 4.6.3 release

---
 .gitmodules     | 4 ++--
 external/libxmp | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/.gitmodules b/.gitmodules
index 146670a9..055e9628 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -26,10 +26,10 @@
 	path = external/mpg123
 	url = https://github.com/libsdl-org/mpg123.git
 	branch = v1.31.3-SDL
-[submodule "libxmp"]
+[submodule "external/libxmp"]
 	path = external/libxmp
 	url = https://github.com/libsdl-org/libxmp.git
-	branch = 4.6.2-SDL
+	branch = 4.6.3-SDL
 [submodule "external/wavpack"]
 	path = external/wavpack
 	url = https://github.com/libsdl-org/wavpack.git
diff --git a/external/libxmp b/external/libxmp
index 9857dcdd..ce107d52 160000
--- a/external/libxmp
+++ b/external/libxmp
@@ -1 +1 @@
-Subproject commit 9857dcdde27a502913d95957c23f7b4e649f8a8a
+Subproject commit ce107d522ee1bd40331b5cba8f81a0aeaf7e1008