Deprecate copy-record in favor of copy-sequence

Deprecate copy-record in favor of copy-sequence

Since copy-sequence seems to be needed anyway for records, have it
work on records, and remove copy-record as being superfluous.
* doc/lispref/records.texi (Records, Record Functions):
* lisp/emacs-lisp/cl-macs.el (cl-defstruct):
* lisp/emacs-lisp/eieio.el (make-instance, clone):
* test/src/alloc-tests.el (record-3):
Use copy-sequence, not copy-record, to copy records.
* doc/lispref/sequences.texi (Sequence Functions)
(Array Functions): Document that aref and copy-sequence
work on records.
* etc/NEWS: Omit copy-record.
* src/alloc.c (Fcopy_record): Remove.
* src/data.c (Faref): Document that arg can be a record.
* src/fns.c (Fcopy_sequence): Copy records, too.