Revision 442981

- Add sndio support [1]
- Remove ALSA from default options
- Switch to options helpers
- Move audio output options to their own option group
- Make OSS support an explicit option, so that it can be turned off
- Remove OGG option and make it mandatory: audio/libogg is already a
  dependency via audio/libvorbis
- Make the port simpler by not building the examples and not
  installing the example games (if necessary installing them can be done
  later in a separate port)
- Add LICENSE
- Fix WWW
- Allegro never directly links with libpng or libGLU; make them a build
  dependency only
- Reset maintainer

PR:		215838
Obtained from:	OpenBSD [1]
Approved by:	mat (mentor), maintainer timeout (5 months)
Differential Revision:	https://reviews.freebsd.org/D11039