format string is not a string literal

[Paul Smith]

On Thu, 2015-02-26 at 18:34 +0000, Pedro Alves wrote:
> Paul, I've improved the comment in vcomplain to clarify
> the solution.  Thanks for poking about that.

Aha thanks; your comment is a little more clear than your email reply; I
was wondering how the compiler could know that the caller's format
string was literal...but from your comment it's clear it just assumes it
if we add proper attributes to vcomplaint().  Spiffy!

Cheers!