tdf#122997 Canceling Paragraph dialog causes crash

regression from
    commit bf359d01
    add a Dialog::runAsync for the non-controller case

Change-Id: I02e3f62b8304139003af1c137ea59750afb4be4c
Reviewed-on: https://gerrit.libreoffice.org/66988
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

vcl/unx/gtk3/gtk3gtkinst.cxx

@@ -2415,8 +2415,10 @@ private:
         hide();
         m_aFunc(GtkToVcl(ret));
         m_aFunc = nullptr;
+        // move the self pointer, otherwise it might be de-allocated by time we try to reset it
+        std::shared_ptr<GtkInstanceDialog> me = std::move(m_xRunAsyncSelf);
         m_xDialogController.reset();
-        m_xRunAsyncSelf.reset();
+        me.reset();
     }
 
 public: