cerbero: Load command-line variants after user config
cerbero: Load command-line variants after user config

So that -v x11 will override `nox11` in the user configuration file.

atsushieno/cerbero,GStreamer/cerbero,GStreamer/cerbero,nirbheek/cerbero,fluendo/cerbero,nirbheek/cerbero,fluendo/cerbero,atsushieno/cerbero,GStreamer/cerbero,atsushieno/cerbero,fluendo/cerbero,GStreamer/cerbero,GStreamer/cerbero,nirbheek/cerbero,fluendo/cerbero,atsushieno/cerbero,fluendo/cerbero,nirbheek/cerbero,atsushieno/cerbero