Update libxml to 2.7.7.

third_party/libxml/catalog.c

 /**
  * catalog.c: set of generic Catalog related routines 
  *
  * Reference:  SGML Open Technical Resolution TR9401:1997.
  *             http://www.jclark.com/sp/catalog.htm
  *
  *             XML Catalogs Working Draft 06 August 2001
  *             http://www.oasis-open.org/committees/entity/spec-2001-08-06.html
  *
  * See Copyright for the status of this software.
@@ skipping 2598 matching lines @@
 
     if (catal->sgml == NULL)
         return(NULL);
 
     if (pubID != NULL)
         ret = xmlCatalogGetSGMLPublic(catal->sgml, pubID);
     if (ret != NULL)
         return(ret);
     if (sysID != NULL)
         ret = xmlCatalogGetSGMLSystem(catal->sgml, sysID);
+    if (ret != NULL)
+        return(ret);
     return(NULL);
 }
 
 /************************************************************************
  *                                                                      *
  *                      Specific Public interfaces                      *
  *                                                                      *
  ************************************************************************/
 
 /**
@@ skipping 276 matching lines @@
 
     if (catal->type == XML_XML_CATALOG_TYPE) {
         ret = xmlCatalogListXMLResolveURI(catal->xml, URI);
         if (ret == XML_CATAL_BREAK)
             ret = NULL;
     } else {
         const xmlChar *sgml;
 
         sgml = xmlCatalogSGMLResolve(catal, NULL, URI);
         if (sgml != NULL)
-            sgml = xmlStrdup(sgml);
+            ret = xmlStrdup(sgml);
     }
     return(ret);
 }
 
 #ifdef LIBXML_OUTPUT_ENABLED
 /**
  * xmlACatalogDump:
  * @catal:  a Catalog
  * @out:  the file.
  *
@@ skipping 887 matching lines @@
     }
 
     if (xmlDefaultCatalog != NULL)
         return(xmlCatalogGetSGMLPublic(xmlDefaultCatalog->sgml, pubID));
     return(NULL);
 }
 
 #define bottom_catalog
 #include "elfgcchack.h"
 #endif /* LIBXML_CATALOG_ENABLED */