Make /var/mail drwxrwxrwt so locking mail files doesn't require setuid.

src/etc/mtree/4.4BSD.dist

@@ -1,4 +1,4 @@
-#	$OpenBSD: 4.4BSD.dist,v 1.22 1996/08/23 15:30:16 etheisen Exp $
+#	$OpenBSD: 4.4BSD.dist,v 1.23 1996/08/27 03:05:33 dm Exp $
 
 /set type=dir uname=root gname=wheel mode=0755
 # .
@@ -1505,7 +1505,7 @@ rdist
 ..
 
 # ./var/mail
-mail
+mail	mode=1777
 # ./var/mail
 ..
 

src/etc/mtree/4.4BSD.var

@@ -1,4 +1,4 @@
-#	$OpenBSD: 4.4BSD.var,v 1.3 1996/08/10 20:54:47 deraadt Exp $
+#	$OpenBSD: 4.4BSD.var,v 1.4 1996/08/27 03:05:36 dm Exp $
 #	$NetBSD: 4.4BSD.var,v 1.3 1996/05/12 23:30:47 thorpej Exp $
 #
 #	   user: bostic
@@ -109,7 +109,7 @@ rdist           type=dir mode=0775
 
 # ./mail
 /set type=file gname=guest uname=root mode=0600
-mail            type=dir uname=root gname=wheel mode=0755
+mail            type=dir uname=root gname=wheel mode=1777
 # ./mail
 ..