Backport some qtbase and qtwayland patches from 5.15 branch
Includes: qtbase: https://codereview.qt-project.org/c/qt/qtbase/+/337969 qtwayland: https://codereview.qt-project.org/c/qt/qtwayland/+/334058 qtwayland: https://codereview.qt-project.org/c/qt/qtwayland/+/333875