headers: crt: disable _wctype global variable in winstore builds

It's not allowed (as far as 2016 doc goes):
https://docs.microsoft.com/en-us/cpp/cppcx/crt-functions-not-supported-in-universal-windows-platform-apps?view=vs-2019

"Multi-byte strings are not supported in UWP apps."

Signed-off-by: Liu Hao <lh_mouse@126.com>
3 files changed