[kokoro] Stop running tests on VS 2013 builds. (#531)
[kokoro] Stop running tests on VS 2013 builds. (#531)


dneto0/shaderc,antiagainst/shaderc,antiagainst/shaderc,antiagainst/shaderc,dneto0/shaderc,antiagainst/shaderc,dneto0/shaderc,dneto0/shaderc