Eliminate msvc compiler warnings (#931)
Eliminate msvc compiler warnings (#931)

The sheer presence of 'std::gmtime' or 'std::localtime' gives rise to C4996 warnings in Microsofts compilers. Alas, the 'fallback(internal::null<>)'functions containing these library calls are never ADL-picked in the respective 'handle(internal::null<>)' selectors. Therefore hiding the fallbacks from msvc is perfectly fine.

alabuzhev/fmt,cppformat/cppformat,cppformat/cppformat,alabuzhev/fmt,cppformat/cppformat,alabuzhev/fmt