Check for a recent enough libmount
Check for a recent enough libmount

We need mnt_unref_table() in order to use libmount, but we also need to
keep the fallback code for installations of libmount without a
pkg-config file.

https://bugzilla.gnome.org/show_bug.cgi?id=782628

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib