evdev: Continue updating axes internally when tool leaves proximity

Axis changes are now still processed by libinput regardless of whether or not
the tool is in proximity, however we refrain from reporting them unless the tool
is in proximity. This stops bad distance events from being reported without
needing a huge mess of conditional statements in sanitize_axes(). The tool is
now counted as back in proximity when a tool update is received instead of when
an axis update is received.

Signed-off-by: Stephen Chandler Paul <thatslyude@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
evdev: Add tablet_mark_all_axes_changed()

Occasionally all the axes that are valid for a device need to be marked as
updated for the caller's sake.

Signed-off-by: Stephen Chandler Paul <thatslyude@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
evdev: Update all axes when the tool comes back into proximity

Signed-off-by: Stephen Chandler Paul <thatslyude@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: Add tests for serial numbers on tools

These tests make sure that any tablets with the capability to report a tool's
serial number do so properly, that the tool changes when another tool of the
same type with a different serial number is used, and that libinput doesn't
change the current tool when -1 is reported as the serial number (-1 is used for
special purposes by the linuxwacom driver).

Signed-off-by: Stephen Chandler Paul <thatslyude@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>