Added check against OSG_GL3_AVAILABLE to avoid issues with GL3 build under linux
Added check against OSG_GL3_AVAILABLE to avoid issues with GL3 build under linux


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