Always use XML_WAR_UNDECLARED_ENTITY with warning error level in
documents with external subset or parameter entities. Use
XML_ERR_UNDECLARED_ENTITY otherwise.
* parser.c: found another bug while looking at #309616 on missing
entities.
* result/ent2.sax* result/ent7.sax* result/xml2.sax*: this changed the
SAX stream in missing conditions for a few tests
Daniel