This adds the management code to manage tablet tools lifetimes from
libinput.
It follows the suggestion made in the tablet-unstable-v2.xml to destroy
tablet_tools once all tablets that it got into contact with were removed
from the system. This is implemented via a refcount.
If a tool is *not* unique, it will be destroyed on proximity out. This
is libinput specific and mentioned in libinput docs that tools will not
be found again, so we shouldn't keep a reference to them.
Also they can't be on other tablets as well, because they cannot be
tracked.
The naming in this commit is a bit off (to not break things).
The wlr names stay the same, tablet_tool is the libinput_device with
capaiblity LIBINPUT_DEVICE_CAP_TABLET_TOOL which is more akin to
"tablet" in the tablet-unstable-v2 protocol.
The struct that corresponds to the tablet_tool in tablet-unstable-v2 is
called tablet_tool_tool, a rename should be done at some point in the
future.
To begin with, no-op updates are unnecessary, so this patch is an
improvement on its own.
Then, this fixes hotplugging issues with xwayland. xwayland waits
for both wl_output and xdg_output to send a "done" event. However,
it doesn't handle well desynchronized "done" updates: if xdg-output
sends "done" twice, the second one will wait for the next wl_output
"done" event. This is an issue when the first is a no-op and the
second is a real update: the second isn't applied. I've considered
patching xwayland instead, but it seems pretty complicated.
It is common to want to iterate an xdg-surface's popups separately from
the toplevel and subsurfaces. For example, popups are typically rendered
on top of most other surfaces.
wlr_xdg_surface_for_each_surface continues to iterate both surfaces and
popups to maintain backwards compatibility.
There was no way to tell wlr_idle to stop processing input events
and rearm timers all the time, such an API is required to have
some form of idle inhibitor.
Detecting whether eglSwapBuffersWithDamageEXT or
eglSwapBuffersWithDamageKHR is used should be based on the extension
string, not only on the availability of the function.
