Update libxml to 2.7.7.

third_party/libxml/include/libxml/parserInternals.h

Index: third_party/libxml/include/libxml/parserInternals.h
diff --git a/third_party/libxml/include/libxml/parserInternals.h b/third_party/libxml/include/libxml/parserInternals.h
index 7ac0ce6eb777014bc3e24fd340c694cc22f4ab93..a5e75b5e386ea2c481a4c698b1434476cda25443 100644
--- a/third_party/libxml/include/libxml/parserInternals.h
+++ b/third_party/libxml/include/libxml/parserInternals.h
@@ -24,18 +24,27 @@ extern "C" {
 /**
  * xmlParserMaxDepth:
  *
- * arbitrary depth limit for the XML documents that we allow to 
- * process. This is not a limitation of the parser but a safety 
- * boundary feature.
+ * arbitrary depth limit for the XML documents that we allow to
+ * process. This is not a limitation of the parser but a safety
+ * boundary feature, use XML_PARSE_HUGE option to override it.
  */
 XMLPUBVAR unsigned int xmlParserMaxDepth;
 
- /**
-  * XML_MAX_NAMELEN:
-  *
-  * Identifiers can be longer, but this will be more costly
-  * at runtime.
-  */
+/**
+ * XML_MAX_TEXT_LENGTH:
+ *
+ * Maximum size allowed for a single text node when building a tree.
+ * This is not a limitation of the parser but a safety boundary feature,
+ * use XML_PARSE_HUGE option to override it.
+ */
+#define XML_MAX_TEXT_LENGTH 10000000
+
+/**
+ * XML_MAX_NAMELEN:
+ *
+ * Identifiers can be longer, but this will be more costly
+ * at runtime.
+ */
 #define XML_MAX_NAMELEN 100
 
 /**
@@ -321,7 +330,7 @@ XMLPUBFUN xmlParserInputPtr XMLCALL
 XMLPUBFUN xmlParserInputPtr XMLCALL	
 			xmlNewEntityInputStream	(xmlParserCtxtPtr ctxt,
 						 xmlEntityPtr entity);
-XMLPUBFUN void XMLCALL			
+XMLPUBFUN int XMLCALL			
 			xmlPushInput		(xmlParserCtxtPtr ctxt,
 						 xmlParserInputPtr input);
 XMLPUBFUN xmlChar XMLCALL