Import smpeg2-2.0.0 as wip/smpeg2.

SMPEG is a free MPEG1 video player library with sound support. Video playback is
based on the ubiquitous Berkeley MPEG player, mpeg_play v2.2. Audio is played
through a slightly modified mpegsound library, part of Splay v0.8.2. SMPEG
supports MPEG audio (MP3), MPEG-1 video, and MPEG system streams.
+smpeg2
Added smpeg2 PKG_OPTION, enabled by default. Removed hard disabling of this
option from Makefile, as upstream split it into a separate package.