New port: audio/sratom

Sratom is a library for serialising LV2 atoms to/from RDF,
particularly the Turtle syntax.

WWW: http://drobilla.net/software/sratom

PR: 213288
Submitted by: Michael Beer <beerml@sigma6audio.de>
Reviewed by: Yuri Victorovich <yuri@rawbw.com>