audio/interna/readerdriver: Bug fix: Potential issue when all the players were gone

When all the players were gone, the waveOut is closed once. From
this state, playing an audio again might take long.

This change fixes the issue by not closing the waveOut even when
all the players are gone.

This change also changes the returning value of read when the
player doesn't play.

audio/internal/readerdriver/driver_windows.go

@@ -178,27 +178,7 @@ func (p *players) removeImpl(player *playerImpl) error {
 	if p.err != nil {
 		return p.err
 	}
-
 	delete(p.players, player)
-	if len(p.players) > 0 {
-		return nil
-	}
-	if p.waveOut == 0 {
-		return nil
-	}
-
-	for _, h := range p.headers {
-		if err := h.Close(); err != nil {
-			return err
-		}
-	}
-	p.headers = p.headers[:0]
-	if err := waveOutClose(p.waveOut); err != nil {
-		return err
-	}
-	p.waveOut = 0
-	p.cond.Signal()
-
 	return nil
 }
 
@@ -616,12 +596,12 @@ func (p *playerImpl) read(buf []byte) int {
 	defer p.m.Unlock()
 
 	if p.state != playerPlay {
-		return len(buf)
+		return 0
 	}
 
 	if len(p.buf) == 0 && p.eof {
 		p.pauseImpl()
-		return len(buf)
+		return 0
 	}
 
 	if len(p.buf) < p.context.maxBufferSize() {