prevent _window_auto_callback from interfering voice system

_window_auto_callback causes interactions, and they interfered voice system in some case.
For example.

        scene bg
        with dissolve

        voice "test.ogg"
        "test"

When "window auto" mode, "test.ogg" is played at the same time as a window begins to be shown. And the say statement stop the voice if preferences.voice_sustain is False.

voice_interact is made not to be called by _window_auto_callback by this pull request.