MSVC x64: Compilation issues with current head and LLVM 3.5 final

[kink via digitalmars-d-ldc]

Hi Kai,

thanks for clarifying the LLVMX86Utils issue.

> I'll switch soon to VS2013. These problems should vanish then.

Great. We'll still need some sort of POSIX layer for the parts 
missing in MSVCRT but required by druntime/Phobos.

For exactly this purpose, I trimmed down the MinGW-w64 CRT a 
while ago (based on v2.0.8) and adapted it so that it can be 
built with Clang in order to get a COFF library suited for the MS 
linker. Additionally, I modified Clang to enable x87 support for 
VS x64 targets, so that MinGW-w64's longdouble functions can be 
used from D.

https://github.com/kinke/mingw-w64-crt