Fix T80282: Playback start delayed with AV sync

If current frame is set to before start frame, with AV sync there is
delay when playback is started.

Tag scene with ID_RECALC_AUDIO_SEEK, so audio playback starts from
correct position.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8809

source/blender/editors/screen/screen_edit.c

@@ -1521,6 +1521,9 @@ void ED_screen_animation_timer(bContext *C, int redraws, int sync, int enable)
     screen->animtimer->customdata = sad;
   }
 
+  /* Seek audio to ensure playback in preview range with AV sync. */
+  DEG_id_tag_update(&scene->id, ID_RECALC_AUDIO_SEEK);
+
   /* notifier catched by top header, for button */
   WM_event_add_notifier(C, NC_SCREEN | ND_ANIMPLAY, NULL);
 }