Add patch for variable KWIN_USE_INTEL_SWAP_EVENT

[xalt7x]

Dear maintainer,

Recently I discovered that KWin's environment variable
KWIN_USE_INTEL_SWAP_EVENT=1
makes a huge difference for latency/smoothness
It was supposed to be enabled in KWin 5.18 but due to "organizational issues with KWin development" Roman Glig reverted his commits.
Improvement of that setting reported users with different GPUs
https://bugs.kde.org/show_bug.cgi?id=344433#c27
https://bugs.kde.org/show_bug.cgi?id=415262#c2

However it introduces problems when compositor state changes. Roman Glig fixed it with really simple patch (which unfortunately also was reverted).

https://phabricator.kde.org/D26090

Could you please cherry-pick it for KWin packages?
Source is trusted, fix confirmed and currently could be easily applied (attached slightly adapted patch).

Thanks.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "Original patch is slightly different, here's adapted version" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

[Scarlett Gately Moore (scarlettmoore)]

THis patch no longer applies. At all. If it is still needed, please provide an updated patch.

[xalt7x (xalt7x)]

@scarlettmoore.
Thanks for reaching out. I believe it was meant to optimize VSync on KWin
Eventually, KWin upstream developers had set KWIN_USE_INTEL_SWAP_EVENT environment variable by default, but then reverted it due to performance issues (https://invent.kde.org/plasma/kwin/-/merge_requests/627). After that KWin, compositor underwent a major refactoring, so I believe those patches shouldn't be applied anymore, and this bug can be closed.