APIs are now per-context rather then per-device. This is leftover from
the no-context-API days.

With this commit, ALSA development packages are no longer required to
build mini_al.

This is internal to ALSA itself, and is fixed by calling
snd_config_update_free_global() when a context is uninitialized. Not
doing this results in Valgrind (and likely other memory leak checkers)
to report errors which is just annoying.