Add a proper type for obarrays

Add a proper type for obarrays

The new opaque type replaces the previous use of vectors for obarrays.
`obarray-make` now returns objects of this type.  Functions that take
obarrays continue to accept vectors for compatibility, now just using
their first slot to store an actual obarray object.

obarray-size and obarray-default-size now obsolete.

* lisp/obarray.el (obarray-default-size, obarray-size):
Declare obsolete.
(obarray-make, obarrayp, obarray-clear): Remove from here.
* src/fns.c (reduce_emacs_uint_to_hash_hash): Remove from here.
* src/lisp.h (struct Lisp_Obarray, OBARRAYP, XOBARRAY, CHECK_OBARRAY)
(make_lisp_obarray, obarray_size, check_obarray)
(obarray_iter_t, make_obarray_iter, obarray_iter_at_end)
(obarray_iter_step, obarray_iter_symbol, DOOBARRAY, knuth_hash): New.
(reduce_emacs_uint_to_hash_hash): Moved here.
* src/lread.c (check_obarray): Renamed and reworked as...
(checked_obarray_slow): ...this.
(intern_sym, Funintern, oblookup, map_obarray)
(Finternal__obarray_buckets): Adapt to new type.
(obarray_index, allocate_obarray, make_obarray, grow_obarray)
(obarray_default_bits, Fobarray_make, Fobarrayp, Fobarray_clear): New.
* etc/emacs_lldb.py (Lisp_Object):
* lisp/emacs-lisp/cl-macs.el (`(,type . ,pred)):
* lisp/emacs-lisp/cl-preloaded.el (cl--typeof-types):
* lisp/emacs-lisp/comp-common.el (comp-known-type-specifiers):
* lisp/emacs-lisp/comp.el (comp-known-predicates):
* src/alloc.c (cleanup_vector, process_mark_stack):
* src/data.c (Ftype_of, syms_of_data):
* src/minibuf.c (Ftry_completion, Fall_completions, Ftest_completion):
* src/pdumper.c (dump_obarray_buckets, dump_obarray, dump_vectorlike):
* src/print.c (print_vectorlike_unreadable):
* test/lisp/abbrev-tests.el (abbrev-make-abbrev-table-test):
* test/lisp/obarray-tests.el (obarrayp-test)
(obarrayp-unchecked-content-test, obarray-make-default-test)
(obarray-make-with-size-test):
Adapt to new type.