main/alsa-lib: enable asserts again
--without-debug flag was added silently in
e7099738. As per
this flag disables assert statements in alsa-lib. This is undesirable
since it makes library usage errors more laborious to debug or
potentially even makes them go unnoticed.
For example, see #12729 (closed) where a null pointer was passed to snd_config_delete by alsa-utils. While the snd_config_delete function in alsa-lib contains an assert checking that the passed config is non-null this assert was disabled due to the aforementioned configure flag.