Comment 8 for bug 1150517

When closing widelands, it's the call in the destructor of songset.
When a music has reached its end It's the other one:

*** glibc detected *** ./widelands: double free or corruption (fasttop): 0x0a531a60 ***
======= Backtrace: =========
/lib/libc.so.6(+0x72ac2)[0xb71b1ac2]
/usr/lib/libSDL-1.2.so.0(SDL_FreeRW+0x1b)[0xb762ff4b]
./widelands(_ZN7Songset8get_songEv+0x163)[0x87f02b5]
./widelands(_ZN13Sound_Handler11start_musicERKSsi+0xca)[0x87ebaaa]
./widelands(_ZN13Sound_Handler12change_musicERKSsii+0xa6)[0x87ebc06]
./widelands(_ZN13WLApplication10poll_eventER9SDL_Eventb+0x168)[0x858372c]
./widelands(_ZN13WLApplication12handle_inputEPK13InputCallback+0x504)[0x8583d98]
./widelands(_ZN2UI5Panel3runEv+0x1bf)[0x86411d7]
./widelands(_ZN9Widelands4Game3runEPN2UI14ProgressWindowENS0_15Start_Game_TypeE+0x7a2)[0x87041c0]
./widelands(_ZN13WLApplication8new_gameEv+0x32f)[0x85889e9]
./widelands(_ZN13WLApplication21mainmenu_singleplayerEv+0x64)[0x8587fde]
./widelands(_ZN13WLApplication8mainmenuEv+0x1a0)[0x8587b82]
./widelands(_ZN13WLApplication3runEv+0x934)[0x8583156]
./widelands(main+0x2f9)[0x8581605]
/lib/libc.so.6(__libc_start_main+0xf5)[0xb71583d5]
./widelands[0x8581241]