Clean up pkg/api.

These are based on recommendation from
[staticcheck](http://staticcheck.io/).

pkg/api/testing/copy_test.go

@@ -69,7 +69,7 @@ func doDeepCopyTest(t *testing.T, kind schema.GroupVersionKind, f *fuzz.Fuzzer)
 		return
 	}
 
-	if bytes.Compare(prefuzzData.Bytes(), postfuzzData.Bytes()) != 0 {
+	if !bytes.Equal(prefuzzData.Bytes(), postfuzzData.Bytes()) {
 		t.Log(diff.StringDiff(prefuzzData.String(), postfuzzData.String()))
 		t.Errorf("Fuzzing copy modified original of %#v", kind)
 		return

pkg/api/testing/serialization_test.go

@@ -387,7 +387,7 @@ func TestObjectWatchFraming(t *testing.T) {
 		}
 		sr = streaming.NewDecoder(framer.NewFrameReader(ioutil.NopCloser(out)), s)
 		outEvent := &metav1.WatchEvent{}
-		res, _, err = sr.Decode(nil, outEvent)
+		_, _, err = sr.Decode(nil, outEvent)
 		if err != nil || outEvent.Type != string(watch.Added) {
 			t.Fatalf("%v: %#v", err, outEvent)
 		}