Fix #30011 & #30027: cycles division by zero evaluating BSDF with zero weights, showed up as NaN on GPU render.
Fix #30011 & #30027: cycles division by zero evaluating BSDF with zero weights,
showed up as NaN on GPU render.


pyrochlore/cycles,pyrochlore/cycles,tangent-opensource/coreBlackbird,pyrochlore/cycles,tangent-opensource/coreBlackbird,tangent-opensource/coreBlackbird