Ensure C++ initializer lists don't get fontified.

Ensure C++ initializer lists don't get fontified.

* lisp/progmodes/cc-cmds.el (c-block-comment-flag): Move declaration to solve
compiler warning.

* lisp/progmodes/cc-fonts.el (c-get-fontification-context): Add an extra
clause to handle C++ member initialization lists.
(c-font-lock-single-decl): New function, extracted from
c-font-lock-declarations.
(c-font-lock-declarations): Call c-font-lock-single-decl in place of inline
code.
(c-font-lock-cut-off-declarators): Make more rigorous by calling
c-get-fontification-context, c-forward-decl-or-cast-1, and
c-font-lock-single-decl in place of rather approximate code.