builtin: add a test for the sorting of []u64 too

vlib/builtin/sorting_test.v

@@ -1,5 +1,5 @@
 const (
-	unsorted = [2,30,10,20,1]
+	unsorted    = [2, 30, 10, 20, 1]
 	sorted_asc  = [1, 2, 10, 20, 30]
 	sorted_desc = [30, 20, 10, 2, 1]
 )
@@ -13,13 +13,12 @@ fn test_sorting_simple() {
 
 fn test_sorting_with_condition_expression() {
 	mut a := unsorted
-	a.sort(a>b)
+	a.sort(a > b)
 	eprintln(' a: $a')
 	assert a == sorted_desc
 }
 
-
-fn mysort (mut a []int) {
+fn mysort(mut a []int) {
 	a.sort()
 }
 
@@ -38,3 +37,12 @@ fn test_sorting_by_passing_an_anonymous_sorting_function() {
 	assert a == sort_desc
 }
 */
+fn test_sorting_u64s() {
+	mut a := [u64(3), 2, 1, 9, 0, 8]
+	a.sort()
+	eprintln(' a: $a')
+	assert a == [u64(0), 1, 2, 3, 8, 9]
+	a.sort(a > b)
+	eprintln(' a: $a')
+	assert a == [u64(9), 8, 3, 2, 1, 0]
+}