SDL_mixer: music.c: added missing Mix_HasMusicDecoder()

SDL Commits
1 
From 8d3c364c7d4cbef2c8e004fad703d841d3272a1c Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Sun, 4 Jul 2021 20:20:00 +0300
Subject: [PATCH] music.c: added missing Mix_HasMusicDecoder()

Noticed by Austin Hurst.
Closes: https://github.com/libsdl-org/SDL_mixer/issues/322
---
 src/music.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/music.c b/src/music.c
index 711f8ba3..b6e8063d 100644
--- a/src/music.c
+++ b/src/music.c
@@ -221,6 +221,17 @@ const char *Mix_GetMusicDecoder(int index)
     return(music_decoders[index]);
 }
 
+SDL_bool Mix_HasMusicDecoder(const char *name)
+{
+    int index;
+    for (index = 0; index < num_decoders; ++index) {
+        if (SDL_strcasecmp(name, music_decoders[index]) == 0) {
+                return SDL_TRUE;
+        }
+    }
+    return SDL_FALSE;
+}
+
 static void add_music_decoder(const char *decoder)
 {
     void *ptr;