Some systems don't define a SIZE_MAX (older versions of HP-UX with aCC).
The logic was already in place to account for this condition but
SIZEOF_SIZE_T was not getting cmoputed at configure time to allow it to
function. This computes sizeof(size_t) at configure time to allow the
appropriate logic to work. It also changes SIZEOF_SIZE_T to SIZE_OF_SIZE_T
for consistency.
Chuck Atkins
Brad King
Daniel Pfeifer