valgrind: memory leaks

Change-Id: If47170b323cb0b48b7cf2182ecbecfac575a6118
(cherry picked from commit 2445de28)
Reviewed-on: https://gerrit.libreoffice.org/19319Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: David Tardon <dtardon@redhat.com>

sw/source/uibase/sidebar/PagePropertyPanel.cxx

@@ -226,6 +226,11 @@ void PagePropertyPanel::dispose()
     m_aSwPageColControl.dispose();
     m_aSwPagePgMetricControl.dispose();
 
+    maColumnPopup.dispose();
+    maSizePopup.dispose();
+    maMarginPopup.dispose();
+    maOrientationPopup.dispose();
+
     PanelLayout::dispose();
 }