ospfd: ABR algorithm not propagating MAXAGE LSAs into area

ospfd: ABR algorithm not propagating MAXAGE LSAs into area

When a range (or sub-range) is deleted, the area is notified by propagating a
MAXAGE LSA.  This LSA stays in the database for a while to both insure
propagation as well as in the off chance that it's useful in the near future.

Unfortunately, the ABR algorithm was treating these MAXAGE LSAs as unchanged and
not propagating them within the areas.

Signed-off-by: JR Rivers <jrrivers@cumulusnetworks.com>
Signed-off-by: Scott Feldman <sfeldma@cumulusnetworks.com>
Reviewed-by: Dinesh Dutt <ddutt@cumulusnetworks.com>
Reviewed-by: Shrijeet Mukherjee <shm@cumulusnetworks.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>