multimedia/mpv: enable more options by default

OPENGL, V4L, VAAPI, VDPAU, XINERAMA, ZSH are now enabled to make package
more useful. OPENGL, VAAPI, VDPAU also support hardware decoding but only
if multimedia/ffmpeg is built with VAAPI, VDPAU (currently off by default).

PR: 203534
Submitted by: tobias.kortkamp@gmail.com
Approved by: Carlos J Puga Medina <cpm@fbsd.es> (maintainer)