* c-decl.c (warn_missing_noreturn): New global variable.
        (c_decode_option): Check for new flags -W{no-}missing-noreturn.
        (finish_function): Implement missing noreturn warning.
        * c-tree.h (warn_missing_noreturn): Declare extern.
        * invoke.texi: Document new flags.
        * toplev.c (documented_lang_options): Add description.

From-SVN: r23197