* lisp.h (struct Lisp_Buffer_Objfwd): Add a `slottype' field.

* lisp.h (struct Lisp_Buffer_Objfwd): Add a `slottype' field.
* data.c (store_symval_forwarding): Get type from buffer_objfwd.
Update call to buffer_slot_type_mismatch.
* buffer.h (buffer_local_types, PER_BUFFER_TYPE): Remove.
(buffer_slot_type_mismatch): Update.
* buffer.c (buffer_local_types): Remove.
(buffer_slot_type_mismatch): Get the symbol and type as arguments.
(defvar_per_buffer): Set the type in the buffer_objfwd.