zeroconf-bonjour: use g_htons() instead of htons()

Fixes the gcc warning "implicit declaration of function 'htons'".

src/zeroconf-bonjour.c

@@ -62,7 +62,7 @@ void init_zeroconf_osx(const char *serviceName)
 	DNSServiceErrorType error = DNSServiceRegister(&dnsReference,
 						       0, 0, serviceName,
 						       SERVICE_TYPE, NULL, NULL,
-						       htons(listen_port), 0,
+						       g_htons(listen_port), 0,
 						       NULL,
 						       dnsRegisterCallback,
 						       NULL);