#7283 Fix crash on exit on centos 7.

[kriben]

Occasionally QGuiApplication::lastWindowClosed() signal could be sent
more than once.

Closes #7283.

[kriben]

This stack trace shows the problem before the fix (stack number 7 and 32):

(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x0000000001fec212 in caf::PdmFieldHandle::~PdmFieldHandle (this=0x39bd900, __in_chrg=<optimized out>) at ../Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmFieldHandle.cpp:54
#2  0x00000000007ad9f4 in RimOilField::~RimOilField (this=0x39bd420, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimOilField.cpp:85
#3  0x00000000007adba9 in RimOilField::~RimOilField (this=0x39bd420, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimOilField.cpp:87
#4  0x00000000007c7198 in caf::PdmChildArrayField<RimOilField*>::deleteAllChildObjects (this=this@entry=0x3881ac0) at ../Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmChildArrayField.inl:164
#5  0x00000000007c23ab in RimProject::close (this=0x38818f0) at ../ApplicationLibCode/ProjectDataModel/RimProject.cpp:251
#6  0x000000000054537f in RiaApplication::closeProject (this=0x37643d0) at ../ApplicationLibCode/Application/RiaApplication.cpp:781
#7  0x0000000000553f0d in RiaGuiApplication::onLastWindowClosed (this=<optimized out>) at ../ApplicationLibCode/Application/RiaGuiApplication.cpp:1622
#8  0x00007ffff5af7bf7 in QMetaObject::activate(QObject*, int, int, void**) () from /lib64/libQt5Core.so.5
#9  0x00007ffff5e31755 in QWindowPrivate::maybeQuitOnLastWindowClosed() () from /lib64/libQt5Gui.so.5
#10 0x00007ffff5e34a81 in QWindowPrivate::destroy() () from /lib64/libQt5Gui.so.5
#11 0x00007ffff636d6a7 in QWidgetPrivate::deleteTLSysExtra() () from /lib64/libQt5Widgets.so.5
#12 0x00007ffff6372438 in QWidget::destroy(bool, bool) () from /lib64/libQt5Widgets.so.5
#13 0x00007ffff637848e in QWidget::~QWidget() () from /lib64/libQt5Widgets.so.5
#14 0x000000000114d112 in RiuViewer::~RiuViewer (this=0x548a0f0, __in_chrg=<optimized out>) at ../ApplicationLibCode/UserInterface/RiuViewer.cpp:226
#15 0x000000000114d309 in RiuViewer::~RiuViewer (this=0x548a0f0, __in_chrg=<optimized out>) at ../ApplicationLibCode/UserInterface/RiuViewer.cpp:242
#16 0x00000000009b1e76 in Rim3dView::~Rim3dView (this=0x44221d0, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/Rim3dView.cpp:194
#17 0x00000000009c8ce0 in RimGridView::~RimGridView (this=0x44221d0, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimGridView.cpp:124
#18 0x00000000008065c9 in RimEclipseView::~RimEclipseView (this=0x44221d0, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimEclipseView.cpp:237
#19 0x00000000007dee78 in caf::PdmChildArrayField<RimEclipseView*>::deleteAllChildObjects (this=this@entry=0x39b4c50) at ../Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmChildArrayField.inl:164
#20 0x00000000007fde4e in RimEclipseResultCase::~RimEclipseResultCase (this=0x39b4810, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimEclipseResultCase.cpp:470
#21 0x00000000007fdfb9 in RimEclipseResultCase::~RimEclipseResultCase (this=0x39b4810, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimEclipseResultCase.cpp:472
#22 0x00000000005c2c48 in caf::PdmChildArrayField<RimEclipseCase*>::deleteAllChildObjects (this=this@entry=0x39b68a0) at ../Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmChildArrayField.inl:164
#23 0x000000000078d4cc in RimEclipseCaseCollection::close (this=this@entry=0x39b6730) at ../ApplicationLibCode/ProjectDataModel/RimEclipseCaseCollection.cpp:70
#24 0x000000000078d52c in RimEclipseCaseCollection::~RimEclipseCaseCollection (this=0x39b6730, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimEclipseCaseCollection.cpp:60
#25 0x000000000078d6b9 in RimEclipseCaseCollection::~RimEclipseCaseCollection (this=0x39b6730, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimEclipseCaseCollection.cpp:61
#26 0x00000000007b11a1 in caf::PdmChildField<RimEclipseCaseCollection*>::~PdmChildField (this=0x39bd590, __in_chrg=<optimized out>) at ../Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmChildField.inl:79
#27 0x00000000007ada6c in RimOilField::~RimOilField (this=0x39bd420, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimOilField.cpp:85
#28 0x00000000007adba9 in RimOilField::~RimOilField (this=0x39bd420, __in_chrg=<optimized out>) at ../ApplicationLibCode/ProjectDataModel/RimOilField.cpp:87
#29 0x00000000007c7198 in caf::PdmChildArrayField<RimOilField*>::deleteAllChildObjects (this=this@entry=0x3881ac0) at ../Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmChildArrayField.inl:164
#30 0x00000000007c23ab in RimProject::close (this=0x38818f0) at ../ApplicationLibCode/ProjectDataModel/RimProject.cpp:251
#31 0x000000000054537f in RiaApplication::closeProject (this=0x37643d0) at ../ApplicationLibCode/Application/RiaApplication.cpp:781
#32 0x0000000000553f0d in RiaGuiApplication::onLastWindowClosed (this=<optimized out>) at ../ApplicationLibCode/Application/RiaGuiApplication.cpp:1622
#33 0x00007ffff5af7bf7 in QMetaObject::activate(QObject*, int, int, void**) () from /lib64/libQt5Core.so.5
#34 0x00007ffff6378060 in QWidgetPrivate::close_helper(QWidgetPrivate::CloseMode) () from /lib64/libQt5Widgets.so.5
#35 0x00000000014629b1 in RicExitApplicationFeature::onActionTriggered (this=<optimized out>, isChecked=<optimized out>) at ../ApplicationLibCode/Commands/ApplicationCommands/RicExitApplicationFeature.cpp:64
#36 0x000000000205a6ee in caf::CmdFeature::actionTriggered (this=0x3aed460, isChecked=<optimized out>) at ../Fwk/AppFwk/cafCommand/cafCmdFeature.cpp:178
#37 0x00007ffff5af7bf7 in QMetaObject::activate(QObject*, int, int, void**) () from /lib64/libQt5Core.so.5
#38 0x00007ffff6338452 in QAction::triggered(bool) () from /lib64/libQt5Widgets.so.5
#39 0x00007ffff633ae2d in QAction::activate(QAction::ActionEvent) () from /lib64/libQt5Widgets.so.5
#40 0x00007ffff64b86f2 in QMenuPrivate::activateCausedStack(QVector<QPointer<QWidget> > const&, QAction*, QAction::ActionEvent, bool) () from /lib64/libQt5Widgets.so.5
#41 0x00007ffff64bf527 in QMenuPrivate::activateAction(QAction*, QAction::ActionEvent, bool) () from /lib64/libQt5Widgets.so.5
#42 0x00007ffff64c045b in QMenu::mouseReleaseEvent(QMouseEvent*) () from /lib64/libQt5Widgets.so.5
#43 0x00007ffff637d1c5 in QWidget::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#44 0x00007ffff64c2893 in QMenu::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#45 0x000000000114ba81 in RiuToolTipMenu::event (this=0x3ae27f0, e=0x7fffffffcfa0) at ../ApplicationLibCode/UserInterface/RiuToolTipMenu.cpp:56
#46 0x00007ffff633ed8c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#47 0x00007ffff6346579 in QApplication::notify(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#48 0x000000000055a8d4 in RiaGuiApplication::notify (this=0x37643c0, receiver=0x3ae27f0, event=0x7fffffffcfa0) at ../ApplicationLibCode/Application/RiaGuiApplication.cpp:1678
#49 0x00007ffff5acfbe6 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#50 0x00007ffff634541c in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) () from /lib64/libQt5Widgets.so.5
#51 0x00007ffff6396444 in QWidgetWindow::handleMouseEvent(QMouseEvent*) () from /lib64/libQt5Widgets.so.5
#52 0x00007ffff6398d65 in QWidgetWindow::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#53 0x00007ffff633ed8c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#54 0x00007ffff6345f68 in QApplication::notify(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#55 0x000000000055a8d4 in RiaGuiApplication::notify (this=0x37643c0, receiver=0x4050d50, event=0x7fffffffd460) at ../ApplicationLibCode/Application/RiaGuiApplication.cpp:1678
#56 0x00007ffff5acfbe6 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#57 0x00007ffff5e2a1ed in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) () from /lib64/libQt5Gui.so.5
#58 0x00007ffff5e2bf25 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) () from /lib64/libQt5Gui.so.5
#59 0x00007ffff5e098db in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Gui.so.5
#60 0x00007fffd5c58950 in userEventSourceDispatch(_GSource*, int (*)(void*), void*) () from /lib64/libQt5XcbQpa.so.5
#61 0x00007fffe9e3e099 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#62 0x00007fffe9e3e3f8 in g_main_context_iterate.isra.19 () from /lib64/libglib-2.0.so.0
#63 0x00007fffe9e3e4ac in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#64 0x00007ffff5b1e45c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#65 0x00007ffff5ace6db in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#66 0x00007ffff5ad6c04 in QCoreApplication::exec() () from /lib64/libQt5Core.so.5
#67 0x00000000004bc30f in main (argc=<optimized out>, argv=<optimized out>) at ../ApplicationExeCode/RiaMain.cpp:130