* lread.c (hash_string): Use size_t, not int, for hash computation.

* lread.c (hash_string): Use size_t, not int, for hash computation.

Normally we prefer signed values; but hashing is special, because
it's better to use unsigned division on hash table sizes so that
the remainder is nonnegative.  Also, size_t is the natural width
for hashing into memory.  The previous code used 'int', which doesn't
retain enough info to hash well into very large tables.
(oblookup, oblookup_last_bucket_number, Funintern): Likewise.