Fix TestReverseSlice for go 1.21

Go 1.21 does a better job using the same empty allocation for empty
slices, check for cap > 0 before requiring slices to have different
backing arrays.

Bug: 309895579
Test: TestReverseSlice
Change-Id: Ic48e9cf2c95ea0b810a11cdc4a794a70c02a0a61

android/util_test.go

@@ -811,7 +811,7 @@ func TestReverseSlice(t *testing.T) {
 			if !reflect.DeepEqual(slice, testCase.expected) {
 				t.Errorf("expected %#v, got %#v", testCase.expected, slice)
 			}
-			if slice != nil && unsafe.SliceData(testCase.in) == unsafe.SliceData(slice) {
+			if cap(slice) > 0 && unsafe.SliceData(testCase.in) == unsafe.SliceData(slice) {
 				t.Errorf("expected slices to have different backing arrays")
 			}
 		})