Update the autotools module so that we can use it to upgrade the
Visual Studio 2010 projects to become Visual Studio 2015-compatible.
Note that this will make the MSVC 2015 builds use the the the latest
VC140 CRT.
Like the Visual Studio 2012 project files, the Visual Studio 2013 files are
largely the same as the Visual Studio 2010 project files, so support
Visual Studio 2013 by updating the autotools scripts that is used for
Visual Studio 2012. This means that project files for Visual Studio 2012
and Visual Studio 2013 can be maintained by simply maintaining the Visual
Studio 2010 project files, adding minimal maintenance overhead.