`QCoreApplicationPrivate::self` is set to nullptr in `~QCoreApplication`
without any synchronization. So it is not safe to access it from
instances of `QDaemonThread` that may outlive the application instance,
but are using the Qt event system. This patch moves some usages of
`self` behind other checks, so that the QtDBus management thread can
continue workoing without race conditions detected by Thread Sanitizer
while running tst_qdbusconnection.
Change-Id: Iece65e4126a59e3a1a41dfb6a99c84527b8d389c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
65953e05d3