Log Message:
SDL2: Audio changes!

SDL_netbsdaudio.c:

* Rework the NetBSD audio driver significantly. Use blocking i/o as
suggested on the SDL bug tracker. Rework the intialization steps
since they were very wrong. All calls to Delay now removed.

* Fixes the horrible stuttering on my system.

* Performance now approximately matches SDL_AUDIODRIVER=dsp. Code
is also closer to SDL_dspaudio.

* Tested with multimedia/mpv, games/etlegacy, emulators/retroarch,
wip/tesseract-game, using SDL audio outputs.

options.mk:

* Add "jack" option, disabled by default.
* Enable ALSA by default on Linux.
* Fix some whitespace problems.

Bump PKGREVISION.