C++ PATCH to prune dead code in constexpr.c

[Jason Merrill]

On 04/15/2015 08:34 AM, Marek Polacek wrote:
> Since r217664 use_new_call is always defined to true, which allows us to
> remove a bit of dead code.  But maybe you'd prefer to keep that #define,
> I don't know.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

Now that we're branched, OK.

Jason