Change default lpd spool directory to match the code; from Chris Bennett

Add /var/spool/output/lpd to mtree(1).
This removes the ability for the daemon group to write directly under
/var/spool/output; though no breakage is expected since this directory was only
supposed to contain line printer spooling directories.
ok sthen@

src/etc/examples/printcap

@@ -1,7 +1,7 @@
-#	$OpenBSD: printcap,v 1.1 2014/07/12 03:52:39 deraadt Exp $
+#	$OpenBSD: printcap,v 1.2 2016/03/05 16:24:56 ajacoutot Exp $
 
 #lp|local line printer:\
-#	:lp=/dev/lp:sd=/var/spool/output:lf=/var/log/lpd-errs:
+#	:lp=/dev/lp:sd=/var/spool/output/lpd:lf=/var/log/lpd-errs:
 
 #rp|remote line printer:\
-#	:lp=:rm=printhost:rp=lp:sd=/var/spool/output:lf=/var/log/lpd-errs:
+#	:lp=:rm=printhost:rp=lp:sd=/var/spool/output/lpd:lf=/var/log/lpd-errs:

src/etc/mtree/4.4BSD.dist

@@ -1,4 +1,4 @@
-#	$OpenBSD: 4.4BSD.dist,v 1.278 2016/01/06 23:28:47 deraadt Exp $
+#	$OpenBSD: 4.4BSD.dist,v 1.279 2016/03/05 16:24:56 ajacoutot Exp $
 
 /set type=dir uname=root gname=wheel mode=0755
 
@@ -757,7 +757,9 @@ var
         # ./var/spool/lock
         lock			uname=uucp gname=dialer mode=1775
         ..
-        output			gname=daemon mode=0775
+        output
+            lpd			gname=daemon mode=0775
+	    ..
         ..
         # ./var/spool/smtpd
         smtpd			type=dir uname=root gname=wheel mode=0711