Update manpage to match source code for --map-file

The manpage had --mapfile but the code had --map-file.

Closes: #606267 in the Debian BTS

Reported-By: Jim Paris <jim@jtan.com>
Signed-off-by: Ron Lee <ron@debian.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/tftpd/tftpd.8.in b/tftpd/tftpd.8.in
index b500d27..71a712d 100644
--- a/tftpd/tftpd.8.in
+++ b/tftpd/tftpd.8.in
@@ -155,7 +155,7 @@
 .B utimeout
 option is negotiated.  The default is 1000000 (1 second.)
 .TP
-\fB\-\-mapfile\fP \fIremap-file\fP, \fB\-m\fP \fIremap-file\fP
+\fB\-\-map-file\fP \fIremap-file\fP, \fB\-m\fP \fIremap-file\fP
 Specify the use of filename remapping.  The
 .I remap-file
 is a file containing the remapping rules.  See the section on filename
@@ -238,7 +238,7 @@
 accepted by the server.
 .SH "FILENAME REMAPPING"
 The
-.B \-\-mapfile
+.B \-\-map-file
 option specifies a file which contains filename remapping rules.  Each
 non-comment line (comments begin with hash marks,
 .BR # )
@@ -398,7 +398,7 @@
 once a connection has been set up.
 .PP
 Finally, the filename remapping
-.RB ( \-\-mapfile
+.RB ( \-\-map-file
 flag) support can be used to provide a limited amount of additional
 access control.
 .SH "CONFORMING TO"