xdiff: backport int64_t and uint64_t types to Windows

Sadly, MSVC 2008 lacks stdint.h.  These are the only two definitions needed
right now.

mercurial/thirdparty/xdiff/xinclude.h

@@ -24,7 +24,13 b''
 #define XINCLUDE_H
 
 #include <ctype.h>
+#if !defined(_MSC_VER) || _MSC_VER >= 1600
 #include <stdint.h>
+#else
+/* prior to Visual Studio 2010 */
+typedef long long int64_t;
+typedef unsigned long long uint64_t;
+#endif
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>