Merge isisd into the Quagga's framework:
  - add privs support
  - use misc quagga's definitions
  - make it compile"able"
  - fix segfault cases related to hostname()
  - add debug isis xxx command

This patch has been approved by Paul Jakma.
diff --git a/zebra/zebra_rib.c b/zebra/zebra_rib.c
index 16102e5..93a13f8 100644
--- a/zebra/zebra_rib.c
+++ b/zebra/zebra_rib.c
@@ -54,6 +54,7 @@
   {ZEBRA_ROUTE_RIPNG,   120},
   {ZEBRA_ROUTE_OSPF,    110},
   {ZEBRA_ROUTE_OSPF6,   110},
+  {ZEBRA_ROUTE_ISIS,    115},
   {ZEBRA_ROUTE_BGP,      20  /* IBGP is 200. */}
 };