pkg-config: Don't fail on format-nonliteral warning
pkg-config: Don't fail on format-nonliteral warning

This otherwise breaks bootstrap on recent GCC.

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