IECoreArnoldPreview/Renderer : as a safety measure, compare pointers
IECoreArnoldPreview/Renderer : as a safety measure, compare pointers

The context is explained in the code. This is essentially just an attempt to
nail down what's causing some of the crashes that we've been seeing lately.

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