when using `-' as a negative sign, escape it with a backslash so troff knows

it's not supposed to be a hyphen/dash

src/lib/libutil/openpty.3

@@ -1,4 +1,4 @@
-.\"	$OpenBSD: openpty.3,v 1.3 1996/11/24 23:53:12 millert Exp $
+.\"	$OpenBSD: openpty.3,v 1.4 1999/07/07 14:22:25 aaron Exp $
 .\" Copyright (c) 1995
 .\"	The Regents of the University of California.  All rights reserved.
 .\"
@@ -118,7 +118,7 @@ If a call to
 .Fn login_tty ,
 or
 .Fn forkpty
-is not successful, -1 is returned and
+is not successful, \-1 is returned and
 .Va errno
 is set to indicate the error.  Otherwise,
 .Fn openpty ,

src/lib/libutil/pw_lock.3

@@ -97,7 +97,7 @@ The
 .Fn pw_lock
 and
 .Fn pw_mkdb
-functions return -1 if they are unable to complete properly.
+functions return \-1 if they are unable to complete properly.
 .Sh FILES
 .Bl -tag -width /etc/master.passwd -compact
 .It Pa /etc/master.passwd

src/lib/libutil/uucplock.3

@@ -21,7 +21,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\" 
-.\" $Id: uucplock.3,v 1.4 1999/07/07 10:50:06 aaron Exp $
+.\" $Id: uucplock.3,v 1.5 1999/07/07 14:22:26 aaron Exp $
 .\" "
 .Dd March 30, 1997
 .Dt uucplock 3
@@ -85,7 +85,7 @@ as returned from
 .Fn uu_lock .
 .Sh RETURN VALUES
 .Fn uu_unlock
-returns 0 on success and -1 on failure.
+returns 0 on success and \-1 on failure.
 .Pp
 .Fn uu_lock
 may return any of the following values: