[Bug c/28901] -Wunused-variable ignores unused const initialised variables

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28901

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
>From the code:
       /* We don't warn about "static const" variables because the
      "rcs_id" idiom uses that construction.  */