Mark DEPRECATED with expiration date 2019-06-15

Rationale:
There has been no active development for several years. The port also
depends on other outdated, unmaintained code, most notably ffmpeg0
which is also scheduled for removal on 2019-06-15.
The functionality provided by this port is available through
multimedia/ffmpeg, which is actively maintained.

PR: 238093
Reported by: tobik