isisd: drop unused per-type metric values

Expense, Error and Delay metrics never quite made it into the real
world.  Either way isisd does nothing useful with them, so let's drop
them from the code.  If someone wants to implement them, this patch can
still be reverted.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/isisd/isis_circuit.h b/isisd/isis_circuit.h
index 9843ef3..9ada1e2 100644
--- a/isisd/isis_circuit.h
+++ b/isisd/isis_circuit.h
@@ -117,7 +117,7 @@
   u_int16_t hello_multiplier[2];	/* l1HelloMultiplier */
   u_int16_t csnp_interval[2];	/* level-1 csnp-interval in seconds */
   u_int16_t psnp_interval[2];	/* level-1 psnp-interval in seconds */
-  struct metric metrics[2];	/* l1XxxMetric */
+  u_int8_t  metric[2];
   u_int32_t te_metric[2];
   struct mpls_te_circuit *mtc; /* Support for MPLS-TE parameters - see isis_te.[c,h] */
   int ip_router;		/* Route IP ? */