mock fix for packages with glib2-devel dependency

[Michael E Brown]

All,

https://bugzilla.redhat.com/show_bug.cgi?id=273481

Builds in mock on x86_64 fail for packages with buildrequires on
glib2-devel. Reported on EPEL 5.

The suggested fix is to add glib2-devel/glib-devel to the exclude list.

Question: is this something we want to apply for FC6/F7/et al?

--
Michael

PS: thanks to Jonathan Steffan for the report and suggested fix.