xdriver_x86-input-joystick: Install server config

xdriver_x86-input-joystick: Install server config

In order for joysticks to be detected and used with this
driver, we need an xorg-server configuration file. This commit
installs such conf file to the default X11 xorg.conf.d path,
so we can at least provide a working template.

Users with specific needs can of course override it.

Signed-off-by: Ezequiel García <ezequiel@vanguardiasur.com.ar>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[Thomas:
 - use XDRIVER_XF86_INPUT_JOYSTICK_PKGDIR
 - remove useless empty line.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>