Instead of separate pairs of short- and long-term maxima for each
measured step of the frame update process.
This should result in the render time estimate rising less often:
Previously it did whenever the measurement of any of at least 3 out of
4 steps reached a new maximum, even if that didn't result in a new
maximum for the whole update duration. Now it's only in the latter
case.
This should also result in a lower render time estimate (and thus
input→output latency) in general, since the variability of
measurements for each 3/4 steps doesn't always add up anymore. The flip
side of this is that it might result in missing a display refresh cycle
more often.
v2:
* Fix coding style in maybe_update_longterm_max_duration_us.
(Robert Mader)
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3090>
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