Mutter already calculates and tracks the damage rectangles to redraw
only areas of the screen that change since the last time a buffer was
used.
This patch extends this by using the EGL_KHR_partial_update extension to
inform the GPU in advance that only those areas will be changed, which
may allow for further optimization.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2023>
577c4711e1