Avoids the WDK include directories hack in MultiAxis' cmake, when possible.

On cmake 2.8.11+, if WDK was found, MultiAxis/CMakeLists.txt causes a
warning about Policy CMP0021.  This warning is due to a hack that adds the
Visual Studio $(IncludePath) property before the WDK include directory.
However, if the try_compile in FindWDK succeeds then WDK does not need any
include directory, and so we can avoid the hack altogether.
Fix cpplint warning cmake-file-not-listed in tryCompileWdk/CMakeLists.txt.
Merge branch 'fix/cmake-wdk-cmp0021-warning' into 'master'

Avoids a warning from the latest cmake due to MultiAxis including the Windows Driver Kit.

+1: gsathyaseelan, Harald Scheirich, Vien Tran

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/622033