Fix crash in wxGenericRichMessageDialog::IsCheckBoxChecked().

The test for checkbox existence was inversed resulting in a guaranteed crash
when calling IsCheckBoxChecked() before showing the dialog.

Closes #12866.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66669 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/richmsgdlgg.cpp

@@ -84,7 +84,7 @@ bool wxGenericRichMessageDialog::IsCheckBoxChecked() const
 {
     // This function can be called before the dialog is shown and hence before
     // the check box is created.
-    return m_checkBox? m_checkBoxValue : m_checkBox->IsChecked();
+    return m_checkBox ? m_checkBox->IsChecked() : m_checkBoxValue;
 }
 
 #endif // wxUSE_RICHMSGDLG