tools: Update endian definitions for Mac OSX

- it appears (at least from OS X verison 10.10, Yosemite) that the
    big and little endian defintions have changed.

    the older

       #include <sys/_endian.h>
       #include <architecture/byte_order.h>

    reference yielded the following warning:

         #define __bswap_16(x)      NXSwapShort(x)
                                    ^
       /usr/include/architecture/byte_order.h:45:1: note: 'NXSwapShort' has been explicitly marked deprecated here

    For the new OS X editions, it seems that we need to refer to:

      #include <netinet/in.h>
      #include <libkern/OSByteOrder.h>

    and respectively use 'OSSwapInt16', 'OSSwapInt32', & 'OSSwapInt64', in
    place of 'NXSwapShort', 'NXSwapLong' & 'NXSwapLongLong'.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>

tools/include/endian.h

@@ -5,11 +5,11 @@
 #include <byteswap.h>
 #include_next <endian.h>
 #elif defined(__APPLE__)
-#include <machine/endian.h>
-#include <machine/byte_order.h>
-#define bswap_16(x) NXSwapShort(x)
-#define bswap_32(x) NXSwapInt(x)
-#define bswap_64(x) NXSwapLongLong(x)
+#include <netinet/in.h>
+#include <libkern/OSByteOrder.h>
+#define bswap_16(x) OSSwapInt16(x)
+#define bswap_32(x) OSSwapInt32(x)
+#define bswap_64(x) OSSwapInt64(x)
 #elif defined(__FreeBSD__)
 #include <sys/endian.h>
 #define bswap_16(x) bswap16(x)