fix for visual studio expres on win7 x86_64 (transplanted from d7e892b4978439c6374d090912f13afa13e8daf8)
fix for visual studio expres on win7 x86_64
(transplanted from d7e892b4978439c6374d090912f13afa13e8daf8)

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