GLWidgetBinding : Fix compilation on OS X.
GLWidgetBinding : Fix compilation on OS X.

andrewkaufman/gaffer,ImageEngine/gaffer,GafferHQ/gaffer,hradec/gaffer,ivanimanishi/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,chippey/gaffer,johnhaddon/gaffer,chippey/gaffer,ImageEngine/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,ImageEngine/gaffer,GafferHQ/gaffer,hradec/gaffer,andrewkaufman/gaffer,hradec/gaffer,boberfly/gaffer,GafferHQ/gaffer,chippey/gaffer,johnhaddon/gaffer,boberfly/gaffer,andrewkaufman/gaffer,lucienfostier/gaffer,ivanimanishi/gaffer,hradec/gaffer,boberfly/gaffer,GafferHQ/gaffer,appleseedhq/gaffer,boberfly/gaffer,johnhaddon/gaffer,ImageEngine/gaffer,chippey/gaffer,hradec/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,lucienfostier/gaffer