Clean out player_+thread_please_stop references.

player.c

@@ -2703,7 +2703,8 @@ int player_play(rtsp_conn_info *conn) {
 }
 
 int player_stop(rtsp_conn_info *conn) {
-  // will only ever be called by the connection thread
+  // note -- this may be called from another connection thread or from the player thread itself
+  // as well as from the conn's own thread.
   debug(3, "player_stop");
   if (conn->player_thread) {
     debug(2, "player_thread cancel...");

player.h

@@ -98,7 +98,6 @@ typedef struct {
   alac_file *decoder_info;
   uint64_t packet_count;
   int connection_state_to_output;
-  int player_thread_please_stop;
   uint64_t first_packet_time_to_play;
   int64_t time_since_play_started; // nanoseconds
                                    // stats