dns: add fixme comment to not block while writing to resolvconf/netconfig

Arguably, a fixme comment isn't useful. It would be better to fix it.
On the other hand, nowadays these modes are not very popular and usually
not used. If somebody cares, please provide a patch.

src/dns/nm-dns-manager.c

@@ -574,6 +574,8 @@ again:
 
 	nm_close (fd);
 
+	/* FIXME: don't write to netconfig synchronously. */
+
 	/* Wait until the process exits */
 	if (!nm_utils_kill_child_sync (pid, 0, LOGD_DNS, "netconfig", &status, 1000, 0)) {
 		errsv = errno;
@@ -751,6 +753,8 @@ dispatch_resolvconf (NMDnsManager *self,
 
 	_LOGI ("Writing DNS information to %s", RESOLVCONF_PATH);
 
+	/* FIXME: don't write to resolvconf synchronously. */
+
 	cmd = g_strconcat (RESOLVCONF_PATH, " -a ", "NetworkManager", NULL);
 	if ((f = popen (cmd, "w")) == NULL) {
 		errsv = errno;