bugfix: alignment calculation on hash-entry.

hkey_offset begins from 13. (3 * sizeof(cl_uint) + sizeof(cl_char)),
then nullmap and hash-key values will follow.
Because of alignment restriction, hash-key has to be placed on the
aligned location. However, we didn't update the offset value on the
deployment of 1st argument. It leads incorrect location to the 2nd
argument.