This commit also fixes a bad bug where initialization will always fail
when initializing from memory.

The reason for this change is to ensure OSS is chosen over JACK by
default on BSD platforms.

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.