[Bug libstdc++/52015] std::to_string does not work under MinGW

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52015

--- Comment #25 from Jonathan Wakely <redi at gcc dot gnu.org> ---
See comment 15 - it's only fixed if you use mingw-w64, and is not possible to
fix for mingw