CVE-2012-0037

Enforce entity loading policy in raptor_libxml_resolveEntity
and raptor_libxml_getEntity by checking for file URIs and network URIs.

Add RAPTOR_OPTION_LOAD_EXTERNAL_ENTITIES / loadExternalEntities for
turning on loading of XML external entity loading, disabled by default.

This affects all the parsers that use SAX2: rdfxml, rss-tag-soup (and
aliases) and rdfa.
raptor_libxml_set_document_locator(void* user_data, xmlSAXLocatorPtr loc)
{
  raptor_sax2* sax2 = (raptor_sax2*)user_data;
  sax2->loc = loc;
}

raptor_libxml_set_document_locator(void* user_data, xmlSAXLocatorPtr loc)
{
  raptor_sax2* sax2 = (raptor_sax2*)user_data;
  sax2->loc = loc;
}
