*: 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/ripd/rip_main.c b/ripd/rip_main.c
index ccb5fa0..6a9fa71 100644
--- a/ripd/rip_main.c
+++ b/ripd/rip_main.c
@@ -275,7 +275,7 @@
 
   /* Library initialization. */
   zprivs_init (&ripd_privs);
-  signal_init (master, Q_SIGC(ripd_signals), ripd_signals);
+  signal_init (master, array_size(ripd_signals), ripd_signals);
   cmd_init (1);
   vty_init (master);
   memory_init ();