Fake proximity events are context dependent and libinput doesn't have access
to the context. For example, fake proximity on the Wacom mouse is only required
in relative mode - but whether to use relative or absolute events is decided
in the caller.
Document what the recommended approach is since it's a bit quirky and leave it
at that.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>