[Bug c/47781] warnings from custom printf format specifiers

[cjwelborn at live dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47781

--- Comment #22 from Cj Welborn <cjwelborn at live dot com> ---
Thank you for the reply. It's probably out of my league, but I might take a
look when I get time.