Add the Q_OS_WIN32 guard for the include of QWinEventNotifier.
Change-Id: I7824b2ee236a370c83fd85a2f594a39cf36b36e6
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>