isisd: address Coverity warnings

this fixes a bunch of issues found by Coverity SCAN and flagged as
"high" impact -- although, they're all rather minute issues.

* isisd/isis_adjacency.c: one superfluous check, one possible NULL deref
* isisd/isis_circuit.c: two prefix memory leaks
* isisd/isis_csm.c: one missing break
* isisd/isis_lsp.c: one possible NULL deref
* isisd/isis_pfpacket.c: one error-case fd leak
* isisd/isis_route.c: one isis_route_info memory leak
* isisd/isis_routemap.c: one... fnord
* isisd/isis_tlv.c: one infinite loop

Reported-by: Coverity SCAN
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/isisd/isis_tlv.c b/isisd/isis_tlv.c
index ed3e0e8..2c2415a 100644
--- a/isisd/isis_tlv.c
+++ b/isisd/isis_tlv.c
@@ -712,6 +712,7 @@
             Neighbor Extended Local Circuit ID (four octets, if Neighbor
               System ID is present) */
 		  pnt += length;
+		  value_len += length;
 		}
 	    }
 	  else