Hang on exit

[glebm]

I got diablo to hang on exit today. I attached to the process with gdb and got this backtrace:

#0  __futex_abstimed_wait_common64 (private=128, cancel=true, abstime=0x0, op=265, expected=25756, futex_word=0x7fb78c647990)
    at ./nptl/futex-internal.c:57
#1  __futex_abstimed_wait_common (cancel=true, private=128, abstime=0x0, clockid=0, expected=25756, futex_word=0x7fb78c647990)
    at ./nptl/futex-internal.c:87
#2  __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x7fb78c647990, expected=25756, clockid=clockid@entry=0, 
    abstime=abstime@entry=0x0, private=private@entry=128) at ./nptl/futex-internal.c:139
#3  0x00007fb7a3091ee3 in __pthread_clockjoin_ex (threadid=140426311136960, thread_return=0x0, clockid=0, abstime=0x0, 
    block=<optimised out>) at ./nptl/pthread_join_common.c:102
#4  0x00007fb7a3e721e5 in ?? () from /lib/x86_64-linux-gnu/libSDL2-2.0.so.0
#5  0x0000561a83becd26 in Aulib::quit () at /home/gleb/devilutionX/build-unpk/_deps/sdl_audiolib-src/src/aulib.cpp:149
#6  0x0000561a83b6e5f3 in devilution::snd_deinit () at /home/gleb/devilutionX/Source/engine/sound.cpp:220
#7  0x0000561a8302606b in devilution::(anonymous namespace)::DiabloDeinit () at /home/gleb/devilutionX/Source/diablo.cpp:1196
#8  0x0000561a8303dc7d in devilution::DiabloMain (argc=4, argv=0x7ffc00843738) at /home/gleb/devilutionX/Source/diablo.cpp:2406
#9  0x0000561a83bb7561 in main (argc=4, argv=0x7ffc00843738) at /home/gleb/devilutionX/Source/main.cpp:52