add some degree of endian detection to hashlittle.cpp

// from lookup3.c, by Bob Jenkins, May 2006, Public Domain

// bob_jenkins@burtleburtle.net

#include "stddef.h"

#include "stdint.h"

#define HASH_LITTLE_ENDIAN 1       // Intel and AMD are little endian

#include <cmath>

#include <stddef.h>

#include <stdint.h>

// if the system defines the __BYTE_ORDER__ define,

// we use it instead of guessing the platform

#if defined(__BYTE_ORDER__)

# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__

#  define HASH_LITTLE_ENDIAN 1

# else

#  define HASH_LITTLE_ENDIAN 0

# endif

#else   // heuristic platform guess

# if defined(__bg__)

#  define HASH_LITTLE_ENDIAN 0       // IBM BlueGene is big endian

# else

#  define HASH_LITTLE_ENDIAN 1       // Intel and AMD x86 are little endian

# endif

#endif

#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))