Passed through from configure.ac via manpages.am

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Matthieu Herrb <matthieu.herrb@laas.fr>
Reviewed-by: Gaetan Nadon <memsize@videotron.ca>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>