Fixed register allocation on function calls

examples/point/point.q

@@ -7,15 +7,15 @@ struct Point {
 }
 
 main() {
-	p := construct()
+	p := construct(1, 2)
 	print(p)
 	delete(p)
 }
 
-construct() -> *Point {
+construct(x Int, y Int) -> *Point {
 	p := new(Point)
-	p.x = 1
-	p.y = 2
+	p.x = x
+	p.y = y
 	return p
 }