Previously we weren't installing the device headers when compiling
without XINPUT support. But we would include them from gdkx.h, so
essentially the build was broken.
With this patch the types will exist but not do anything.
Moving the direct-access redefinitions of various macros
to gdkprivate-x11.h and use that header throughout in x11/.
Also remove a workaround for a long-fixed X server bug.
* _gdk_device_set_associated_device() did not allow NULL device
* GdkDisplay should dispose device manager to avoid devices
trying to touch the display in finalize
* GdkDeviceManagerXI did not ref devices in id hash
* GdkDisplayX11 did not ref devices in ->input_devices