Changes to make `narrow-to-defun' and `mark-defun' work properly in CC

Changes to make `narrow-to-defun' and `mark-defun' work properly in CC
Mode:

cc-defs.el (c-beginning-of-defun-1):
cc-cmds.el (c-beginning-of-defun, c-end-of-defun): bind
beginning/end-of-defun-function to nil around calls to
beginning/end-of-defun.

cc-langs.el (beginning-of-defun-function, end-of-defun-function): new
c-lang-setvar's.

cc-awk.el (c-awk-beginning-of-defun): Add "(or arg (setq arg 1))" to
enable non-interactive call.