Fix array.reverse() test

vlib/builtin/array_test.v

@@ -149,9 +149,14 @@ fn test_push_many() {
 }
 
 fn test_reverse() {
-	mut a := [1, 2, 3, 4]
+  	mut a := [1, 2, 3, 4]
 	mut b := ['test', 'array', 'reverse']
-
+	c := a.reverse()
-	assert a.reverse() == [4, 3, 2, 1]
+	d := b.reverse()
-	assert b.reverse() == ['reverse', 'array', 'test']
+	for i, _  in c {
+		assert c[i] == a[a.len-i-1]
+	}
+	for i, _ in d {
+		assert d[i] == b[b.len-i-1]
+	}
 }