avformat/mov: reset drefs_count in close

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/oggdec: reset nstreams in close

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Read aspect ratio from tiff image files.
Fix standalone compilation of vp7 and vp8 decoder.

Fixes ticket #3536.