xcb: avoid to use invalid pointers
Pick-to: 6.2 5.15 5.12 Task-number: QTBUG-96399 Change-Id: I33909940b501cb13f78981c43f3aef9fc9d1d52d Reviewed-by: Shawn Rutledge shawn.rutledge@qt.io (cherry picked from commit e0938223)
Pick-to: 6.2 5.15 5.12 Task-number: QTBUG-96399 Change-Id: I33909940b501cb13f78981c43f3aef9fc9d1d52d Reviewed-by: Shawn Rutledge shawn.rutledge@qt.io (cherry picked from commit e0938223)