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/lib/command.c b/lib/command.c
index 43a0bb3..2411306 100644
--- a/lib/command.c
+++ b/lib/command.c
@@ -2325,6 +2325,7 @@
     case RIPNG_NODE:
     case OSPF_NODE:
     case OSPF6_NODE:
+    case ISIS_NODE:
     case KEYCHAIN_NODE:
     case MASC_NODE:
     case RMAP_NODE:
@@ -2377,6 +2378,7 @@
     case RMAP_NODE:
     case OSPF_NODE:
     case OSPF6_NODE:
+    case ISIS_NODE:
     case KEYCHAIN_NODE:
     case KEYCHAIN_KEY_NODE:
     case MASC_NODE: