Fix issue 2421 by not trying to use os.chown on Windows.
Fix issue 2421 by not trying to use os.chown on Windows.

andrewyoung1991/scons,timj/scons,timj/scons,timj/scons,timj/scons,timj/scons,andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,timj/scons,andrewyoung1991/scons,andrewyoung1991/scons