*: 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/ripngd/ripng_main.c b/ripngd/ripng_main.c
index f4a6244..20225b7 100644
--- a/ripngd/ripng_main.c
+++ b/ripngd/ripng_main.c
@@ -272,7 +272,7 @@
 
   /* Library inits. */
   zprivs_init (&ripngd_privs);
-  signal_init (master, Q_SIGC(ripng_signals), ripng_signals);
+  signal_init (master, array_size(ripng_signals), ripng_signals);
   cmd_init (1);
   vty_init (master);
   memory_init ();