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

[josh at joshtriplett dot org]

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

--- Comment #24 from Josh Triplett <josh at joshtriplett dot org> ---
Also, even the documentation seems unfortunate: "In C++ this is normally not an
error since const variables take the place of #defines in C++."

Why would C code not do this too?  The GCC documentation should not steer
people away from this practice in C, or imply that there's something wrong with
it.