OpenAL needs -pthread
On FreeBSD (and maybe NetBSD as well), OpenAL needs -pthread in
CFLAGS/LDFLAGS:
configure:2352: gcc -o conftest -I/usr/local/include -L/usr/local/lib
conftest.c -lopenal >&5
/usr/local/lib/libopenal.so: undefined reference to `pthread_create'
/usr/local/lib/libopenal.so: undefined reference to `pthread_attr_init'
/usr/local/lib/libopenal.so: undefined reference to `pthread_exit'
This should best be solved during configure instead of setting this
globally. Also, this probably needs to be propagated into OpenAL.
cabal for linking a resulting application (although already the RTS
should pull in -pthread).