Jon Turney authored Apr 09, 2014 and Hugo Beauzée-Luyssen committed Dec 20, 2017

Use __USE_MINGW_ANSI_STDIO for ANSI C99 compatible implementation of printf()
and friends on MinGW

Perhaps we don't need this, if all the printf formats used are in the subset
supported by MSVCRT, but it's easier to turn this on than audit every
single format string...