Adds the following quartett of functions to enable/disable middle mouse button
emulation on a device:
libinput_device_config_middle_emulation_is_available()
libinput_device_config_middle_emulation_set_enabled()
libinput_device_config_middle_emulation_get_enabled()
libinput_device_config_middle_emulation_get_default_enabled()
This patch only adds the config framework, it is not hooked up to anything
yet.
Note: like other features this is merely the config option, some devices will
provide middle button emulation without exposing it as configuration. i.e. the
return value of libinput_device_config_middle_emulation_is_available() only
tells you whether you can _configure_ middle button emulation.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
