Add some "safe-local-variable" declarations for compatibility with master.

Add some "safe-local-variable" declarations for compatibility with master.

These enable C files from the master repository to be visited in Emacs 25
without generating irritating questions about configuration variable safety.

* lisp/progmodes/cc-vars.el: (c-string-list-p, c-string-or-string-list-p): New
functions.
(c-noise-macro-names, c-noise-macro-with-parens-names): give the
safe-local-variable property c-string-list-p.
(c-macro-names-with-semicolon): give the safe-local-variable property
c-string-or-string-list-p.