add new signed datatype

src/headers/tomcrypt_cfg.h

@@ -206,9 +206,11 @@ LTC_EXPORT int   LTC_CALL XSTRCMP(const char *s1, const char *s2);
 #ifdef _MSC_VER
    #define CONST64(n) n ## ui64
    typedef unsigned __int64 ulong64;
+   typedef __int64 long64;
 #else
    #define CONST64(n) n ## ULL
    typedef unsigned long long ulong64;
+   typedef long long long64;
 #endif
 
 /* ulong32: "32-bit at least" data type */