Small cleanup (#877)

* Remove unused variables and constants
* Remove redundant return statement
* Change flock.NewFlock to flock.New

audio/vorbis/vorbis.go

@@ -71,7 +71,6 @@ type decoder interface {
 
 type decoded struct {
 	totalBytes int
-	readBytes  int
 	posInBytes int
 	source     io.Closer
 	decoder    decoder

internal/graphicsdriver/opengl/program.go

@@ -151,11 +151,6 @@ var (
 	zeroProgram program
 )
 
-const (
-	maxTriangles = graphics.IndicesNum / 3
-	maxQuads     = maxTriangles / 2
-)
-
 // reset resets or initializes the OpenGL state.
 func (s *openGLState) reset(context *context) error {
 	if err := context.reset(); err != nil {

internal/restorable/images_test.go

@@ -432,11 +432,6 @@ func TestRestoreRecursive(t *testing.T) {
 }
 
 func TestReplacePixels(t *testing.T) {
-	const (
-		w = 17
-		h = 31
-	)
-
 	img := NewImage(17, 31)
 	defer img.Dispose()
 

internal/shareable/shareable.go

@@ -468,7 +468,6 @@ func (i *Image) allocate(shareable bool) {
 	i.backend = b
 	i.node = n
 	runtime.SetFinalizer(i, (*Image).Dispose)
-	return
 }
 
 func (i *Image) MakeVolatile() {

internal/testflock/flock_notjs.go

@@ -28,7 +28,7 @@ import (
 	"github.com/gofrs/flock"
 )
 
-var theLock = flock.NewFlock(filepath.Join(os.TempDir(), "ebitentest"))
+var theLock = flock.New(filepath.Join(os.TempDir(), "ebitentest"))
 
 func Lock() {
 	if err := theLock.Lock(); err != nil {