gunixmounts: Fix mount points generation
gunixmounts: Fix mount points generation

Commit 53ed180 improved mtab processing, however, also introduced bug
in code obtaining mount points. mtab was used by mistake also for
g_unix_mount_points_get implementation, which is obviously wrong and
fstab has to be used instead...

https://bugzilla.gnome.org/show_bug.cgi?id=781867

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