D22737: xcb: Fix setStrut() for High-DPI scaling

[Alexander Volkov]

volkov added a reviewer: Frameworks.

REPOSITORY
  R278 KWindowSystem

REVISION DETAIL
  https://phabricator.kde.org/D22737

To: volkov, #frameworks
Cc: kde-frameworks-devel, LeGast00n, sbergeron, michaelh, ngraham, bruns