Changes

Define __USE_MINGW_ANSI_STDIO=0 for mingw-w64 (#9939)

The latest mingw-w64 _mingw.h header now automatically sets __USE_MINGW_ANSI_STDIO=1 for C99 and later. mingw-w64 always defines snprintf but the inline definition when __USE_MINGW_ANSI_STDIO=0 temporarily #undef's any snprintf macro so works in harmony with ours. The other case does not do this so we get declaration errors.

Fixes: #9938 .
(cherry picked from commit a03b6035ebe4682950018e0e1337bab18771fd81)
 (commit: 26ebd64)