vc1: Fix pic_header_flag=0 (SA10143.vc1)
Bug introduced in:
commit 4509be3d2f46a52ada8e2ecb476faed93e19abf3
Author: Michael Niedermayer <michaelni@gmx.at>
Date:   Tue Oct 11 11:56:42 2011 +0200

    vc1: reset interlaced variables, prevent another bunch of crashes.

    Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
