Increase chase cam target trace distance

Allows for chasecam to function in large open maps, useful for the
func_vehicle mod where people naturally want to create open maps.
Patch suggested by Marko Permanto, based on a commit in Ironwail by
Andrei Drexler.
https://sourceforge.net/p/quakespasm/patches/34/
6e55a30c90

Quake/chase.c

@@ -106,7 +106,7 @@ void Chase_UpdateForDrawing (void)
 	VectorCopy (ideal, r_refdef.vieworg);
 
 	// find the spot the player is looking at
-	VectorMA (cl.viewent.origin, 4096, forward, temp);
+	VectorMA (cl.viewent.origin, 1<<20, forward, temp);
 	TraceLine (cl.viewent.origin, temp, crosshair);
 
 	// calculate camera angles to look at the same spot