Update expat to 2.2.0 to fix CVE vulnerability.

third_party/expat/files/lib/expat.h

 /* Copyright (c) 1998, 1999, 2000 Thai Open Source Software Center Ltd
    See the file COPYING for copying permission.
 */
 
 #ifndef Expat_INCLUDED
 #define Expat_INCLUDED 1
 
 #ifdef __VMS
 /*      0        1         2         3      0        1         2         3
         1234567890123456789012345678901     1234567890123456789012345678901 */
@@ skipping 324 matching lines @@
                               const XML_Char *base,
                               const XML_Char *systemId,
                               const XML_Char *publicId,
                               const XML_Char *notationName);
 
 XMLPARSEAPI(void)
 XML_SetEntityDeclHandler(XML_Parser parser,
                          XML_EntityDeclHandler handler);
 
 /* OBSOLETE -- OBSOLETE -- OBSOLETE
-   This handler has been superceded by the EntityDeclHandler above.
+   This handler has been superseded by the EntityDeclHandler above.
    It is provided here for backward compatibility.
 
    This is called for a declaration of an unparsed (NDATA) entity.
    The base argument is whatever was set by XML_SetBase. The
    entityName, systemId and notationName arguments will never be
    NULL. The other arguments may be.
 */
 typedef void (XMLCALL *XML_UnparsedEntityDeclHandler) (
                                     void *userData,
                                     const XML_Char *entityName,
@@ skipping 610 matching lines @@
 #define XML_GetErrorLineNumber   XML_GetCurrentLineNumber
 #define XML_GetErrorColumnNumber XML_GetCurrentColumnNumber
 #define XML_GetErrorByteIndex    XML_GetCurrentByteIndex
 
 /* Frees the content model passed to the element declaration handler */
 XMLPARSEAPI(void)
 XML_FreeContentModel(XML_Parser parser, XML_Content *model);
 
 /* Exposing the memory handling functions used in Expat */
 XMLPARSEAPI(void *)
+XML_ATTR_MALLOC
+XML_ATTR_ALLOC_SIZE(2)
 XML_MemMalloc(XML_Parser parser, size_t size);
 
 XMLPARSEAPI(void *)
+XML_ATTR_ALLOC_SIZE(3)
 XML_MemRealloc(XML_Parser parser, void *ptr, size_t size);
 
 XMLPARSEAPI(void)
 XML_MemFree(XML_Parser parser, void *ptr);
 
 /* Frees memory used by the parser. */
 XMLPARSEAPI(void)
 XML_ParserFree(XML_Parser parser);
 
 /* Returns a string describing the error. */
@@ skipping 35 matching lines @@
 typedef struct {
   enum XML_FeatureEnum  feature;
   const XML_LChar       *name;
   long int              value;
 } XML_Feature;
 
 XMLPARSEAPI(const XML_Feature *)
 XML_GetFeatureList(void);
 
 
-/* Expat follows the GNU/Linux convention of odd number minor version for
-   beta/development releases and even number minor version for stable
-   releases. Micro is bumped with each release, and set to 0 with each
-   change to major or minor version.
+/* Expat follows the semantic versioning convention.
+   See http://semver.org.
 */
 #define XML_MAJOR_VERSION 2
-#define XML_MINOR_VERSION 1
+#define XML_MINOR_VERSION 2
 #define XML_MICRO_VERSION 0
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif /* not Expat_INCLUDED */