C++ Mode: handle comma separated brace initializers.

C++ Mode: handle comma separated brace initializers.

This includes both indentation and fontification.

* lisp/progmodes/cc-engine.el (c-do-declarators): Handle brace initializers
without = correctly.
(c-looking-at-or-maybe-in-bracelist): Use c-do-declarators with a simple
inline function to check that after-type-id-pos points to the start of a
declarator.

* lisp/progmodes/cc-langs.el (c-recognize-bare-brace-inits): New lang
const/variable.