don't call playerStop() before playerPlay()

Since playerPlay() already calls playerStop(), we can remove its
invocation of playerStop() from playPlaylistOrderNumber().

We can also make playerStop a static function.

src/player.c

@@ -52,14 +52,6 @@ void player_command_finished()
 }
 
 void playerPlay(Song * song)
-{
-	playerStop();
-
-	set_current_song(song);
-	player_command(PLAYER_COMMAND_PLAY);
-}
-
-void playerStop(void)
 {
 	assert(pc.queueLockState == PLAYER_QUEUE_UNLOCKED);
 
@@ -67,6 +59,9 @@ void playerStop(void)
 		player_command(PLAYER_COMMAND_STOP);
 
 	pc.queueState = PLAYER_QUEUE_BLANK;
+
+	set_current_song(song);
+	player_command(PLAYER_COMMAND_PLAY);
 }
 
 void playerWait(void)

src/player.h

@@ -109,8 +109,6 @@ void playerSetPause(int pause_flag);
 
 void playerPause(void);
 
-void playerStop(void);
-
 void playerKill(void);
 
 int getPlayerTotalTime(void);

src/playlist.c

@@ -837,8 +837,6 @@ static void playPlaylistOrderNumber(int orderNum)
 {
 	char path_max_tmp[MPD_PATH_MAX];
 
-	playerStop();
-
 	playlist_state = PLAYLIST_STATE_PLAY;
 	playlist_noGoToNext = 0;
 	playlist.queued = -1;