Revision 1770677

Make the XML parser stricter by prohibiting custom XML entities.

* subversion/libsvn_subr/xml.c
  (expat_entity_declaration, expat_default_handler): New.
  (svn_xml_make_parser, svn_xml_signal_bailout): Install new handlers.

* subversion/tests/libsvn_subr/xml-test.c
  (test_xml_builtin_entity_expansion, test_xml_custom_entity_expansion,
   test_xml_doctype_declaration): New tests.
  (test_funcs): Reference new tests.