Error found in code that allows dynamic octrees. A lookup table was not

cleared correctly for each face, causing too many octree nodes to be
filled in.
Especially for more complex scenes this fix is quite a time saver.

Still looking at ways to speedup octree filling though.

source/blender/render/intern/source/ray.c

@@ -540,7 +540,7 @@ void makeoctree()
 				}
 			}
 			
-			memset(ocvlak, 0, sizeof(ocvlak));
+			memset(ocvlak, 0, 3*ocres2);
 			
 			for(c=0;c<3;c++) {
 				oc1= rts[0][c];