Don't Xr flock, since that is not the locking method used.

ok millert

src/lib/libutil/pw_lock.3

@@ -1,4 +1,4 @@
-.\"	$OpenBSD: pw_lock.3,v 1.18 2015/09/14 13:45:25 schwarze Exp $
+.\"	$OpenBSD: pw_lock.3,v 1.19 2015/10/15 19:35:24 deraadt Exp $
 .\"
 .\" Copyright (c) 1995
 .\"	The Regents of the University of California.  All rights reserved.
@@ -31,7 +31,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: September 14 2015 $
+.Dd $Mdocdate: October 15 2015 $
 .Dt PW_LOCK 3
 .Os
 .Sh NAME
@@ -151,7 +151,6 @@ may also fail and set
 for any of the errors specified for the routine
 .Xr open 2 .
 .Sh SEE ALSO
-.Xr flock 2 ,
 .Xr pw_file 3 ,
 .Xr pw_init 3 ,
 .Xr pwd_mkdb 8