let the compiler check format strings

let the compiler check format strings

i'll be AFK for a week, so here's the patch i've been using this
evening to find other format string mistakes. BSD uses __printflike
and takes two arguments instead of hard-coding (1,2), but i figured
that as long as you don't need the generality you'd prefer not to have
it. and it's easy enough to retrofit if we ever do have a formatting
function that takes other arguments.