Require Visual Studio 2015 or later.

Something about Visual Studio 2013 causes test failures,
but I currently have no idea what that could be because
there is no output from the failed tests whatsoever. :(

Change-Id: Ic57cba54115ededa738ed42f4fffe5dd2d6350de
Reviewed-on: https://code-review.googlesource.com/20930
Reviewed-by: Paul Wankadia <junyer@google.com>
1 file changed