[Super-tux-devel] Sound (again) bugs fixed

[Duong-Khang N. <neo...@us...>]

Changes:

1. Bug fixed: start with sound off (via menu) then sound on (via menu) didn't
work. Now it works correctly.

2. Changes introduced by the point 1: sound.c will load song and music even if
"use_sound" is 0

3. Fixed memory leaks in sound/song/gfx un/loading. It's just a temporary 
solution until the point 4 is fixed.

4. IMHO: one function should have only one return instruction. Multiple return
statements are the cause of bug in point 3.