vtysh: fix the fix for babeld removal... (5460bae)

Commit 5460bae ("*: fix 'babeld: Remove babeld from Quagga' (336724d)")
unfortunately removed the BABEL_NODE from vtysh, which now no longer
starts.

Fix by restoring the node (even though it won't be accessible).

Reported-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Fixes: 5460bae ("*: fix 'babeld: Remove babeld from Quagga' (336724d)")
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/vtysh/vtysh.c b/vtysh/vtysh.c
index e2d63f9..b33ac90 100644
--- a/vtysh/vtysh.c
+++ b/vtysh/vtysh.c
@@ -798,6 +798,12 @@
   "%s(config-ospf6)# "
 };
 
+static struct cmd_node babel_node =
+{
+  BABEL_NODE,
+  "%s(config-babel)# "
+};
+
 static struct cmd_node keychain_node =
 {
   KEYCHAIN_NODE,
@@ -2248,6 +2254,7 @@
   install_node (&ripng_node, NULL);
   install_node (&ospf6_node, NULL);
 /* #endif */
+  install_node (&babel_node, NULL);
   install_node (&keychain_node, NULL);
   install_node (&keychain_key_node, NULL);
   install_node (&isis_node, NULL);