Added assertions to most tests

tests/programs/math.q

@@ -1,6 +1,7 @@
 main() {
 	x := 1000
-	syscall(60, div10(x) / 10 + div(x, 100) * 4 - 40 - x + x)
+	result := div10(x) / 10 + div(x, 100) * 4 - 40 - x + x
+	assert result == 10
 }
 
 div(x, y) {