OpenGLRenderer : Fix deletion of cameras
OpenGLRenderer : Fix deletion of cameras

This was leading to cameras never being removed from the Gaffer viewer.

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