C++ PATCH to fix naked inform call for strong using directive

[Jason Merrill]

On 5/20/19 11:56 AM, Marek Polacek wrote:
> This patch fixes a naked inform call that can be seen with -w.
> 
> While at it, I added missing quotes; I'm surprisesd this wasn't fixed by the
> recent patch Martin submitted.
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

OK.  We might also change "may" to "can" in the inform.

Jason