- oren nayar call didnt return float value... but still worked on my

system, and gcc refuses to see it as warning. weirdos!
  this caused previewrender to show black for oren nayar.

source/blender/render/intern/source/rendercore.c

@@ -1543,7 +1543,7 @@ float OrenNayar_Diff_i(float nl, float *n, float *l, float *v, float rough )
 float OrenNayar_Diff(float *n, float *l, float *v, float rough )
 {
 	float nl= n[0]*l[0] + n[1]*l[1] + n[2]*l[2];
-	OrenNayar_Diff_i(nl, n, l, v, rough);
+	return OrenNayar_Diff_i(nl, n, l, v, rough);
 }