configure: Use a single required version for GLib
configure: Use a single required version for GLib

Both GObject and GIO are part of GLib, so there's no
point in requiring different versions of the two.

Signed-off-by: Andrea Bolognani <3ada0bee826c753786fdbba72243dfba997094cf@redhat.com>
Reviewed-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

libvirt/libvirt-sandbox,libvirt/libvirt-sandbox,libvirt/libvirt-sandbox