* ma_rb_reset()
* ma_rb_available_read()
* ma_rb_available_write()
* ma_pcm_rb_reset()
* ma_pcm_rb_available_read()
* ma_pcm_rb_available_write()

Fix a few tiny memory leaks

This happens when stopping the device while nothing is being played and
is due to how WASAPI does not signal an event in loopback mode when
nothing is being played.

These are not used by miniaudio and are just a waste of maintenance
costs. Only libraries that are actually used by miniaudio will be
included in the extras directory from now on.