Fix -fno-common build error. Taken from
https://svnweb.freebsd.org/ports?view=revision&revision=549579

Index: mdnsd/mdnsd.c
--- mdnsd/mdnsd.c.orig
+++ mdnsd/mdnsd.c
@@ -45,6 +45,8 @@ int		mdns_sock(void);
 void		fetchmyname(char [MAXHOSTNAMELEN]);
 void		fetchhinfo(struct hinfo *);
 
+ctl_conns_t	ctl_conns;
+
 struct mdnsd_conf	*conf = NULL;
 extern char		*malloc_options;