All or almost all the warnings seen on Windows/Mingw of the type
"warning: unknown conversion type character 'm' in format" come from
checking of three functions: errmsg, elog and errdetail. I therefore
propose to disable the attribute checking of those three functions, on
Windows only (since that's the only place I've seen the warnings).
That's a much more conservative change than I made previously which
would have turned off all format warnings on Mingw, and along with
fixing the INT64_FORMAT (see email just sent) would fix the vast
majority of compiler warnings, so we'd be almost clean again on MinGW.
cheers
andrew