as told in _eina_stringshared_key_cmp in eina_hash.c:
ogically we want to do this:
return key1 - key2;
but since they are ptrs and an int can't store the different of 2 ptrs in
either 32 or 64bit (signed hasn't got enough range for the diff of 2
32bit values regardless of their type... we'd need 33bits or 65bits)
So changing this to the same logic.