I was trying to update pulseaudio but it fails in configure "... X11 not found". Sure enough # ls /usr/*/pkgconfig/*X11* /usr/lib64/pkgconfig/Qt5X11Extras.pc I've rebuild everything with X11 in its name (5 packages), also anything with "xorg" in its name (drivers, proto, and server). I was expecting x11-libs/libX11 to provide /usr/lib/pgkconfig/X11, but it doesn't and neither do any of the others. Note that I've had a great number of configure errors since moving to the 17.1 profiles, and found them easy to solve. If some strange package provides the .pc file it should be easier to find.
if you look for the correct file, then you will find it: ls /usr/*/pkgconfig/*x11*
if you have a problem with pulseaudio's configure, make a bug about it and attach the build.log and config.log
Created 690554.