decoder: reorder a variable initialization
decoder: reorder a variable initialization

There are no needs to keep a copy of this on the stack. Besides, the
value could change if we supported threaded audio decoding.

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc