eglfs: Call destroy() from dtors of concrete windows

Calling destroy from the QEglFSWindow dtor() triggers the virtual
invalidateSurface() to be called on a partly destroyed object. As the
child windows deregister themselves from their screens on
invalidateSurface() this is dangerous: It leaves a dangling pointer in
the screen.

Fixes: QTBUG-75075
Change-Id: Idd3fea18562d41973f364340df875a50dbd5691e
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

src/plugins/platforms/eglfs/api/qeglfswindow.cpp

@@ -167,6 +167,9 @@ void QEglFSWindow::create()
 
 void QEglFSWindow::destroy()
 {
+    if (!m_flags.testFlag(Created))
+        return; // already destroyed
+
 #ifndef QT_NO_OPENGL
     QOpenGLCompositor::instance()->removeWindow(this);
 #endif

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmwindow.h

@@ -55,6 +55,9 @@ public:
         : QEglFSWindow(w),
           m_integration(integration)
     { }
+
+    ~QEglFSKmsGbmWindow() { destroy(); }
+
     void resetSurface() override;
     void invalidateSurface() override;
 

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp

@@ -116,6 +116,8 @@ public:
         , m_egl_stream(EGL_NO_STREAM_KHR)
     { }
 
+    ~QEglFSKmsEglDeviceWindow() { destroy(); }
+
     void invalidateSurface() override;
     void resetSurface() override;
 

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_vsp2/qeglfskmsvsp2integration.cpp

@@ -205,6 +205,9 @@ public:
         : QEglFSWindow(w)
         , m_integration(integration)
     {}
+
+    ~QEglFSKmsVsp2Window() { destroy(); }
+
     void resetSurface() override;
     void invalidateSurface() override;
     const QEglFSKmsVsp2Integration *m_integration;