undefined identifier FILE for mingw

[kinke]

On Monday, 6 July 2020 at 13:49:31 UTC, Innot Sagg wrote:
> To fix this in druntime, we need a new version like: 
> CRuntime_Mingw ?
>
> or should reuse CRuntime_Glibc ?

Yeah, MinGW is a mess - it's actually based on the MS runtime, 
but overrides some MS symbols (e.g., all `long double` math 
functions, because they use 80-bit, not 64-bit as MSVC, and so 
also the scanf/printf function families) and adds some new 
functions for C99/Posix/GNU compatibility. [Most of these are 
obsolete by now since the MS runtime provides almost full C99 
compatibility since their 2015 runtime.]

So in some cases, it would be CRuntime_Microsoft, in others 
CRuntime_Glibc, and in some others probably resorting to already 
existing version `MinGW` to differentiate.