From David Spilling, fix for VS6.0 build.
From David Spilling, fix for VS6.0 build.


marchelbling/osg,jtorresfabra/osg,tomasthoresen/osg,marchelbling/osg,artoolkit/osg,openscenegraph/osg,tomasthoresen/osg,tomasthoresen/osg,artoolkit/osg,scrawl/osg,marchelbling/osg,openscenegraph/osg,scrawl/osg,scrawl/osg,openscenegraph/osg,openscenegraph/osg,jtorresfabra/osg,scrawl/osg,jtorresfabra/osg,marchelbling/osg,tomasthoresen/osg,artoolkit/osg,artoolkit/osg,jtorresfabra/osg