Update expat to 2.2.0 to fix CVE vulnerability.

third_party/expat/files/lib/xmltok.h

 /* Copyright (c) 1998, 1999 Thai Open Source Software Center Ltd
    See the file COPYING for copying permission.
 */
 
 #ifndef XmlTok_INCLUDED
 #define XmlTok_INCLUDED 1
 
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ skipping 112 matching lines @@
 } ATTRIBUTE;
 
 struct encoding;
 typedef struct encoding ENCODING;
 
 typedef int (PTRCALL *SCANNER)(const ENCODING *,
                                const char *,
                                const char *,
                                const char **);
 
+enum XML_Convert_Result {
+  XML_CONVERT_COMPLETED = 0,
+  XML_CONVERT_INPUT_INCOMPLETE = 1,
+  XML_CONVERT_OUTPUT_EXHAUSTED = 2  /* and therefore potentially input remaining as well */
+};
+
 struct encoding {
   SCANNER scanners[XML_N_STATES];
   SCANNER literalScanners[XML_N_LITERAL_TYPES];
   int (PTRCALL *sameName)(const ENCODING *,
                           const char *,
                           const char *);
   int (PTRCALL *nameMatchesAscii)(const ENCODING *,
                                   const char *,
                                   const char *,
                                   const char *);
   int (PTRFASTCALL *nameLength)(const ENCODING *, const char *);
   const char *(PTRFASTCALL *skipS)(const ENCODING *, const char *);
   int (PTRCALL *getAtts)(const ENCODING *enc,
                          const char *ptr,
                          int attsMax,
                          ATTRIBUTE *atts);
   int (PTRFASTCALL *charRefNumber)(const ENCODING *enc, const char *ptr);
   int (PTRCALL *predefinedEntityName)(const ENCODING *,
                                       const char *,
                                       const char *);
   void (PTRCALL *updatePosition)(const ENCODING *,
                                  const char *ptr,
                                  const char *end,
                                  POSITION *);
   int (PTRCALL *isPublicId)(const ENCODING *enc,
                             const char *ptr,
                             const char *end,
                             const char **badPtr);
-  void (PTRCALL *utf8Convert)(const ENCODING *enc,
+  enum XML_Convert_Result (PTRCALL *utf8Convert)(const ENCODING *enc,
                               const char **fromP,
                               const char *fromLim,
                               char **toP,
                               const char *toLim);
-  void (PTRCALL *utf16Convert)(const ENCODING *enc,
+  enum XML_Convert_Result (PTRCALL *utf16Convert)(const ENCODING *enc,
                                const char **fromP,
                                const char *fromLim,
                                unsigned short **toP,
                                const unsigned short *toLim);
   int minBytesPerChar;
   char isUtf8;
   char isUtf16;
 };
 
 /* Scan the string starting at ptr until the end of the next complete
@@ skipping 130 matching lines @@
 ENCODING *
 XmlInitUnknownEncodingNS(void *mem,
                          int *table,
                          CONVERTER convert,
                          void *userData);
 #ifdef __cplusplus
 }
 #endif
 
 #endif /* not XmlTok_INCLUDED */