Add a warning message to mountd for exported file

systems that are automounted, since that configuration
isn't supported. This still allows the export, since
two emails I received felt that this should not be
disabled. It sends the message to syslog(LOG_ERR..), so that
it goes to the same places as the other messages related
to /etc/exports problems, even though it is a warning and not an error.

Reviewed by:	trasz
MFC after:	2 weeks

usr.sbin/mountd/mountd.c

@@ -1410,6 +1410,9 @@ get_exportlist_one(void)
 			    }
 			    if (check_dirpath(cp) &&
 				statfs(cp, &fsb) >= 0) {
+				if ((fsb.f_flags & MNT_AUTOMOUNTED) != 0)
+				    syslog(LOG_ERR, "Warning: exporting of "
+					"automounted fs %s not supported", cp);
 				if (got_nondir) {
 				    syslog(LOG_ERR, "dirs must be first");
 				    getexp_err(ep, tgrp);