D27788: Implement EGL_KHR_partial_update

apol created this revision.
apol added reviewers: KWin, Plasma: Mobile.
Herald added a project: KWin.
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REVISION SUMMARY
  Notify the driver about the parts of the screen that will be repainted.
  In some cases this can be benefitial. This is especially useful on lima
  and panfrost devices (e.g. pinephone, pinebook, pinebook pro).

TEST PLAN
  Tested on a pinebook pro with a late mesa version.
  Basically I implemented it, then it didn't work and I fixed it.
  Maybe next step we want to look into our damage algorithm.

REPOSITORY
  R108 KWin

BRANCH
  master

REVISION DETAIL
  https://phabricator.kde.org/D27788

AFFECTED FILES
  platformsupport/scenes/opengl/abstract_egl_backend.cpp
  platformsupport/scenes/opengl/backend.h
  plugins/platforms/drm/egl_gbm_backend.cpp

To: apol, #kwin, #plasma:_mobile
Cc: kwin, Orage, LeGast00n, The-Feren-OS-Dev, cblack, jraleigh, zachus, fbampaloukas, GB_2, mkulinski, ragreen, jackyalcine, iodelay, crozbo, bwowk, ZrenBot, ngraham, alexeymin, himcesjf, lesliezhai, ali-mohamed, hardening, romangg, jensreuterberg, abetts, sebas, apol, ahiemstra, mart