r242766 - Fix mingw toolchain to honor sysroot on Linux and add tests.

[Hans Wennborg]

Merged to 3.7 (together with r242662) in r243063.

On Tue, Jul 21, 2015 at 4:01 AM, Yaron Keren <yaron.keren at gmail.com> wrote:
> Author: yrnkrn
> Date: Tue Jul 21 06:01:00 2015
> New Revision: 242766
>
> URL: http://llvm.org/viewvc/llvm-project?rev=242766&view=rev
> Log:
> Fix mingw toolchain to honor sysroot on Linux and add tests.
>
> It should now support three mingw distributions running on Windows
> and three Linux distributions. The include directories for each are
> listed in the comments.