bgpd: improve cleanup in bgp_delete()

Signed-off-by: Lou Berger <lberger@labn.net>
diff --git a/bgpd/bgpd.h b/bgpd/bgpd.h
index 2c4fb20..0b3d449 100644
--- a/bgpd/bgpd.h
+++ b/bgpd/bgpd.h
@@ -123,6 +123,7 @@
 #define BGP_FLAG_GRACEFUL_RESTART         (1 << 12)
 #define BGP_FLAG_ASPATH_CONFED            (1 << 13)
 #define BGP_FLAG_ASPATH_MULTIPATH_RELAX   (1 << 14)
+#define BGP_FLAG_DELETING                 (1 << 15)
 
   /* BGP Per AF flags */
   u_int16_t af_flags[AFI_MAX][SAFI_MAX];