Fix NAME section of manpages zhack and fsck.zfs.

In Debian GNU/Linux a program called 'linitian' is used to make sure
that packages conforms to the Debian GNU/Linux packaging guide lines.
This fixes the problem reported as:

     W: zfsutils: manpage-has-bad-whatis-entry usr/share/man/man1/zhack.1.gz
     W: zfsutils: manpage-has-bad-whatis-entry usr/share/man/man8/fsck.zfs.8.gz

Not something that ZoL needs to addhere to, but every other man page
have their NAME section in a special way - why not these two as well?

Signed-off-by: Turbo Fredriksson <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes openzfs#2161

man/man1/zhack.1

@@ -23,8 +23,9 @@
 .\" Copyright 2013 Darik Horn <[email protected]>. All rights reserved.
 .\"
 .TH zhack 1 "2013 MAR 16" "ZFS on Linux" "User Commands"
+
 .SH NAME
-.BR zhack " \- libzpool debugging tool"
+zhack \- libzpool debugging tool
 .SH DESCRIPTION
 This utility pokes configuration changes directly into a ZFS pool,
 which is dangerous and can cause data corruption.

man/man8/fsck.zfs.8

@@ -25,7 +25,7 @@
 .TH fsck.zfs 8 "2013 MAR 16" "ZFS on Linux" "System Administration Commands"
 
 .SH NAME
-.BR fsck.zfs " \- Dummy ZFS filesystem checker."
+fsck.zfs \- Dummy ZFS filesystem checker.
 
 .SH SYNOPSIS
 .LP