[cleanup] convert bzero() deprecated by POSIX to memset()

autoscan 2.62 complains about bzero(), so a good fix
nowadays is to just replace it.
diff --git a/zebra/irdp_packet.c b/zebra/irdp_packet.c
index 3c5f155..6003837 100644
--- a/zebra/irdp_packet.c
+++ b/zebra/irdp_packet.c
@@ -332,7 +332,7 @@
 	zlog_warn("sendto %s", safe_strerror (errno));
   }
 
-  bzero(&sockdst,sizeof(sockdst));
+  memset(&sockdst,0,sizeof(sockdst));
   sockdst.sin_family=AF_INET;
   sockdst.sin_addr.s_addr = dst;