make getSecurityQuery public, so that restricted environement can use portal_catalog.buildSQLQuery(query=portal_catalog.getSecurityQuery(), **kw) to build security aware queries



git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@13302 20353a03-c40f-0410-a6d1-a30d3c3de9de