Fix double free of libinput_device_group
Starting with libinput-1.1.0 libinput tries to clean up device group objects when destroying the libinput context, even when they are still referneced by libinput_device objects. To ensure we do not free device groups twice the libinput context is kept alive by LibInputDevicePtr. .
Approved by Alberto Aguirre, PS Jenkins bot, Cemil Azizoglu.