In rBA6aa8e130eff59059886e203ff95221609f63b222 all
occurrences of "lamp" where replaced with "light" which
also accidentally renamed "clamp" to "clight". All incorrect
usages of `clight` are replaced with `clamp` in this patch.

Reviewed By: mont29

Differential Revision: https://developer.blender.org/D9783