Cycles: Prevent NaN and inf in area lamp sampling caused by precision issues
Cycles: Prevent NaN and inf in area lamp sampling caused by precision issues

This doesn't have noticeable affect on the render times, but avoids possible
numerical issues.

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