Stop polluting syslog(3).

Index: avahi-compat-libdns_sd/warn.c
--- avahi-compat-libdns_sd/warn.c.orig
+++ avahi-compat-libdns_sd/warn.c
@@ -110,11 +110,13 @@ void avahi_warn_linkage(void) {
     linkage_warning = 1;
     pthread_mutex_unlock(&linkage_mutex);
 
+#if 0
     if (!w && !getenv("AVAHI_COMPAT_NOWARN")) {
         avahi_warn("The program '%s' uses the "COMPAT_LAYER" compatibility layer of Avahi.", avahi_exe_name());
         avahi_warn("Please fix your application to use the native API of Avahi!");
         avahi_warn("For more information see <http://0pointer.de/blog/projects/avahi-compat.html>");
     }
+#endif
 }
 
 void avahi_warn_unsupported(const char *function) {