- removed bogus assert in SW's track setup.

One of the stock maps (WT $airport map.) triggers this assert so it cannot remain.

source/games/sw/src/track.cpp

@@ -677,7 +677,6 @@ TrackSetup(void)
             // save the closest one off and kill it
             if (next_sprite != -1)
             {
-                ASSERT(low_dist < 20000);
                 TrackAddPoint(t, tp, next_sprite);
             }