sys-utils: correct setarch.8 manpage link creation

sys-utils: correct setarch.8 manpage link creation

At least on Debian, .so commands are relative to the man directory
(e.g., /usr/share/man), not to the subdirectory:
    % man i386
    man: can't open /usr/share/man/setarch.8: No such file or directory
    No manual entry for i386

See also http://bugs.debian.org/453245

Addresses-Debian-Bug: #453245
Signed-off-by: Frédéric Bothamy <frederic.bothamy@free.fr>
Signed-off-by: LaMont Jones <lamont@debian.org>
Signed-off-by: Karel Zak <kzak@redhat.com>