Fix typo in change_smoothing_half_life.

This caused a minor loss of accuracy.

route.c

@@ -596,7 +596,7 @@ change_smoothing_half_life(int half_life)
     case 1: two_to_the_one_over_hl = 131072; break;
     case 2: two_to_the_one_over_hl = 92682; break;
     case 3: two_to_the_one_over_hl = 82570; break;
-    case 4: two_to_the_one_over_hl = 77935;
+    case 4: two_to_the_one_over_hl = 77935; break;
     default:
         /* 1/2^(1/x) is 1 + log(2)/x + O(1/x^2) at infinity. */
         two_to_the_one_over_hl = 0x10000 + 45426 / half_life;