SDL_mixer: Back out master volume affecting music

SDL Commits
1 
From c0f1cffbbf8f693ad74a1be51b44d6f7fed661ba Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 27 May 2022 13:05:54 -0700
Subject: [PATCH] Back out master volume affecting music

---
 src/music.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/music.c b/src/music.c
index 8263128d..6ef8047d 100644
--- a/src/music.c
+++ b/src/music.c
@@ -324,14 +324,14 @@ void SDLCALL music_mixer(void *udata, Uint8 *stream, int len)
         /* Handle fading */
         if (music_playing->fading != MIX_NO_FADING) {
             if (music_playing->fade_step++ < music_playing->fade_steps) {
-                int volume = Mix_MasterVolume(-1);
+                int volume;
                 int fade_step = music_playing->fade_step;
                 int fade_steps = music_playing->fade_steps;
 
                 if (music_playing->fading == MIX_FADING_OUT) {
-                    volume = (volume * (music_volume * (fade_steps-fade_step))) / (fade_steps * MIX_MAX_VOLUME);
+                    volume = (music_volume * (fade_steps-fade_step)) / fade_steps;
                 } else { /* Fading in */
-                    volume = (volume * (music_volume * fade_step)) / (fade_steps * MIX_MAX_VOLUME);
+                    volume = ( music_volume * fade_step ) / fade_steps;
                 }
                 music_internal_volume(volume);
             } else {