cmake-mode.el: drop reserved keybindings (#14576)

The keybindings added by commit 301e67e3 (cmake-mode.el: add local
keybindings, 2012-09-20) overlap the reserved C-c space:

 http://www.gnu.org/software/emacs/manual/html_node/elisp/Key-Binding-Conventions.html

Revert the commit to drop them.

Reported-by: Paul Smith <paul@mad-scientist.net>
Reviewed-by: Eric NOULARD <eric.noulard@gmail.com>
Merge topic 'emacs-mode-no-reserved-bindings' into next

0f21261 cmake-mode.el: drop reserved keybindings (#14576)