Re-add removed block:

Christian Biere suggests it was a typo, and was intended to describe
ENFILE; let it do that.

lib/libc/sys/fcntl.2

@@ -1,4 +1,4 @@
-.\"	$NetBSD: fcntl.2,v 1.33 2007/01/03 23:02:53 wiz Exp $
+.\"	$NetBSD: fcntl.2,v 1.34 2007/01/04 00:02:43 wiz Exp $
 .\"
 .\" Copyright (c) 1983, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -479,6 +479,12 @@ process are already in use,
 or no file descriptors greater than or equal to
 .Fa arg
 are available.
+.It Bq Er ENFILE
+.Fa cmd
+is
+.Dv F_DUPFD
+and system-wide the maximum allowed number of file descriptors are
+currently open.
 .It Bq Er ENOLCK
 The argument
 .Fa cmd