bgpd: drop unused static variable

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c
index be316da..5c832ed 100644
--- a/bgpd/bgp_attr.c
+++ b/bgpd/bgp_attr.c
@@ -72,7 +72,6 @@
   /* bgp_attr_flags_diagnose() relies on this bit being last in this list */
   { BGP_ATTR_FLAG_EXTLEN,   "Extended Length" },
 };
-static const size_t attr_flag_str_max = array_size(attr_flag_str);
 
 static struct hash *cluster_hash;