Optimize: We can early out of LOIT_ClipLumObjBySight as soon as we de…

…termine the lumobj is clipped.

doomsday/engine/portable/src/r_lumobjs.c

@@ -839,6 +839,7 @@ boolean LOIT_ClipLumObjBySight(void* data, void* context)
                                  seg->SG_v2pos, NULL, NULL, NULL))
                 {
                     luminousClipped[lumIdx] = 1;
+                    break;
                 }
             }
         }