Install LLVM toolset extension

Hi,

I am working on a cross-platform C11 project, thus I cannot use the MSVC compiler. LLVM is already installed in the windows travis environment but not the llvm toolchain extension.

Best-case scenario would of course be this extension to be preinstalled, but for now I have to resort to downloading and installing it myself with a small bash script. This VSIX extension should be installed via the VSIXInstaller.exe which is located deep inside the install folder of visual studio, but it is reachable when the Native Tools Command Prompt is used.

Is there a way to find out where Visual Studio is installed to so I can work myself towards this VSIXInstaller?