[player] Save seek position more often

Makes it possible for the user to resume playback from the correct position if
for instance the speaker disconnects -> pb_abort is called.

src/player.c

@@ -1666,6 +1666,8 @@ pb_session_pause(void)
 {
   pb_timer_stop();
 
+  seek_save();
+
   source_stop();
 }
 
@@ -1675,6 +1677,8 @@ pb_session_stop(void)
 {
   pb_timer_stop();
 
+  seek_save();
+
   source_stop();
 
   session_stop();
@@ -2347,8 +2351,6 @@ playback_pause_bh(void *arg, int *retval)
 
   status_update(PLAY_PAUSED);
 
-  seek_save();
-
   *retval = 0;
   return COMMAND_END;