On LLP64 platforms (e.g. Win64), unsigned long (32-bit)
cannot cover the memory address (64-bit). FT_MEM_VAL() is
used for hashing only and not dereferred, so using signed
type FT_PtrDist is safe.
* src/base/ftdbgmem.c (FT_MEM_VAL): Change the type of the
return value from FT_ULong to FT_PtrDist.
(ft_mem_table_resize): The type of hash is changed to
FT_PtrDist. (ft_mem_table_get_nodep): Ditto.