list: deprecate list.map.

* specs/list_spec.yaml (map): Specify output of deprecation
warning on first call.
* specs/debug_spec.yaml (debug, say): Use functional.map for
mkwrap instead of deprecated list.map.
* lib/std/list.lua (map): Deprecate.
* NEWS: Update.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>