*: use array_size() helper macro

Use the array_size() helper macro.  Replaces several instances of local
macros with the same definition.

Reviewed-by: Scott Feldman <sfeldma@cumulusnetworks.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/isisd/isis_main.c b/isisd/isis_main.c
index f5266aa..dcbc3de 100644
--- a/isisd/isis_main.c
+++ b/isisd/isis_main.c
@@ -325,7 +325,7 @@
    *  initializations
    */
   zprivs_init (&isisd_privs);
-  signal_init (master, Q_SIGC (isisd_signals), isisd_signals);
+  signal_init (master, array_size (isisd_signals), isisd_signals);
   cmd_init (1);
   vty_init (master);
   memory_init ();