isisd: Fix LSPs not being regenerated after adjacency change

In isisd LSP's are not regenerated after a change in adjacency if
lsp-gen-interval has expired.
I have tested this on Debian 6.0 with zebra and level1 isisd with point
to point links. This problem is also listed in Test ISIS-18.3 on the
opensourcerouting.org wiki:
http://confluence.isc.org/display/osr/ANVL+ISIS+Compliance+Test+Plan
http://confluence.isc.org/display/osr/ANVL+ISIS+Results
1 file changed