Simplify the adjust_varying calls in fresnel -- no need to check variable pairs for aliasing if they are not of the same type (for example, a vector and a float CANNOT be aliases of the same variable).
Simplify the adjust_varying calls in fresnel -- no need to check variable
pairs for aliasing if they are not of the same type (for example, a vector
and a float CANNOT be aliases of the same variable).

h3rb/openshadinglanguage,qdtk/openshadinglanguage,code-google-com/openshadinglanguage,code-google-com/openshadinglanguage,qdtk/openshadinglanguage,h3rb/openshadinglanguage,tectronics/openshadinglanguage,code-google-com/openshadinglanguage,tectronics/openshadinglanguage,code-google-com/openshadinglanguage,qdtk/openshadinglanguage,h3rb/openshadinglanguage,h3rb/openshadinglanguage,tectronics/openshadinglanguage,tectronics/openshadinglanguage,qdtk/openshadinglanguage