simplify the endianity handling

src/borg/algorithms/msgpack/sysdep.h

@@ -66,18 +66,9 @@ typedef unsigned int _msgpack_atomic_counter_t;
 #endif
 
 #if !defined(__LITTLE_ENDIAN__) && !defined(__BIG_ENDIAN__)
-/*
- * __BYTE_ORDER, __LITTLE_ENDIAN and __BIG_ENDIAN are nonstandard and not
- * always available. In those cases, fallback to common compiler defines.
- */
-#if !defined(__BYTE_ORDER)
-#define __BYTE_ORDER __BYTE_ORDER__
-#define __LITTLE_ENDIAN __ORDER_LITTLE_ENDIAN__
-#define __BIG_ENDIAN __ORDER_BIG_ENDIAN__
-#endif
-#if __BYTE_ORDER == __LITTLE_ENDIAN
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 #define __LITTLE_ENDIAN__
-#elif __BYTE_ORDER == __BIG_ENDIAN
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 #define __BIG_ENDIAN__
 #elif _WIN32
 #define __LITTLE_ENDIAN__