* When postgres.h does not define BYTE_ENDIAN pgcrypto

* When postgres.h does not define BYTE_ENDIAN pgcrypto
  produces garbage.

I learned the hard way that

        #if UNDEFINED_1 == UNDEFINED_2
        #error "gcc is idiot"
        #endif

prints "gcc is idiot" ...

Affected are MD5/SHA1 in internal library, and also HMAC-MD5/HMAC-SHA1/
crypt-md5 which use them.  Blowfish is ok, also Rijndael on at
least x86.

Big thanks to Daniel Holtzman who send me a build log which
contained warning:

        md5.c:246: warning: `X' defined but not used

Yes, gcc is that helpful...

Please apply this.

--
marko