We've removed the old style .pc files which were specific to Fedora from
xulrunner-devel and now are using only the upstream versions.
In short, if you were using:
mozilla-embedding.pc
xulrunner-embedding.pc
you must now use:
libxul-embedding.pc
and if you were using:
mozilla-xpcom.pc
xulrunner-xpcom.pc
Please see
http://fedoraproject.org/wiki/Releases/FeatureXULRunnerAPIChanges for
details as always.