[ospfd] Bug #330 regression: Fix ospf_spf_add_parent assert

[ospfd] Bug #330 regression: Fix ospf_spf_add_parent assert

2007-05-07 Paul Jakma <paul.jakma@sun.com>

	* ospf_spf.c: (ospf_vertex_new) Dont init vertices to infinity,
	  just let 0 be a special case.
	  (ospf_spf_add_parent) 0 distance candidate vertex is special,
	  cost still to be initialised - asserting that new distance
	  is <= existing only makes sense where w already has a cost.
	  (ospf_spf_next) Infinite cost links should not be followed,
	  bar those of the root.