Modified fair layouts' behaviors when there is only 2 windows to
manage.
In this case each layout adopt the behavior of the other so as to look
consistent with their name.
fairv: +-----+
| | |
| | |
+-----+
fairh: +-----+
|_____|
| |
+-----+
Signed-off-by: Gwenhael Le Moine <gwenhael.le.moine@gmail.com>
Signed-off-by: Julien Danjou <julien@danjou.info>