Merge from vendor branch TNF:

Merge from vendor branch TNF:
Import gst123-0.1.4 as multimedia/gst123

The program gst123 is designed to be a more flexible command line
player in the spirit of ogg123 and mpg123, based on gstreamer. It
plays all file formats gstreamer understands, so if you have a
music collection which contains different file formats, like flac,
ogg and mp3, you can use gst123 to play all your music and video
files.

It is implemented in C++ and licensed under the GNU LGPL version 2.