[isisd] Fix compiler warnings and allow v4-only compilation

[isisd] Fix compiler warnings and allow v4-only compilation

2006-12-08 Hannes Gredler <hannes@gredler.at>

	* isis_adjacency.c: (isis_new_adj) Allow NULL snpa argument.
	* isis_pdu.c: (various) Update calls to isis_new_adj() to pass
	  NULL and use default.
	* (general) Add forward declarations where required.
	  Fix up const char *'s.
	  Allow V4-only compilation.