Don't access QObject::objectName during QThread start
This is a data race, as the thread accesses QObject::objectName on the QThread instance while the thread owning the QThread might modify the objectName.
Instead, make a copy in the QThreadPrivate that can be accessed safely.
Task-number: QTBUG-96718 Pick-to: 6.3 6.2 5.15 Change-Id: I10701551d498993ca5055daf161636bfb648840c Reviewed-by: Marc Mutz marc.mutz@qt.io (cherry picked from commit 4a4240f1)