Cycles OSL: refactoring to remove all dependencies on builtin OSL closures.

These were removed in new OSL versions. We only used these as base classes,
not using them at all simplifies the code a bit.

intern/cycles/kernel/kernel_shader.h

@@ -764,11 +764,6 @@ ccl_device float3 shader_bssrdf_sum(ShaderData *sd, float3 *N_, float *texture_b
 
 ccl_device float3 emissive_eval(KernelGlobals *kg, ShaderData *sd, ShaderClosure *sc)
 {
-#ifdef __OSL__
-	if(kg->osl && sc->prim)
-		return OSLShader::emissive_eval(sd, sc);
-#endif
-
 	return emissive_simple_eval(sd->Ng, sd->I);
 }