Remove an erroneous interactive specification from two functions.
* lisp/progmodes/cc-cmds.el (c-display-defun-name): New command.
(c-defun-name, c-cpp-define-name): Remove interactive specification.
* lisp/progmodes/cc-mode.el (c-mode-base-map): Add binding C-c C-z for the new
command.
* doc/misc/cc-mode.texi (Other Commands): Add documentation for the new
command.
