SDL_mixer: Bump mpg123 to include i686-android patch

From 32ff5654aeb13bb475c7909be89303152d921105 Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Wed, 12 Oct 2022 03:15:42 +0200
Subject: [PATCH] Bump mpg123 to include i686-android patch

---
 external/mpg123 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/external/mpg123 b/external/mpg123
index 0b973cd5..5475987f 160000
--- a/external/mpg123
+++ b/external/mpg123
@@ -1 +1 @@
-Subproject commit 0b973cd5d6de30c98d957aade824807d846049ee
+Subproject commit 5475987f8fb303daf692f3167f5e81506e3c0dcf