hash: Extend the byte order check to cover x86_64.

ccan/hash/hash.c

@@ -54,7 +54,8 @@ on 1 byte), but shoehorning those bytes into integers efficiently is messy.
 #if (defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && \
      __BYTE_ORDER == __LITTLE_ENDIAN) || \
     (defined(i386) || defined(__i386__) || defined(__i486__) || \
-     defined(__i586__) || defined(__i686__) || defined(vax) || defined(MIPSEL))
+     defined(__i586__) || defined(__i686__) || defined(__x86_64) || \
+     defined(vax) || defined(MIPSEL))
 # define HASH_LITTLE_ENDIAN 1
 # define HASH_BIG_ENDIAN 0
 #elif (defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) && \