lavc: Don't export ff_vdpau_vc1_decode_picture

It's not our responsibility to account for other projects'
terrible hacky usage.

Also, it is no longer needed by XMBC, since 78b71d4.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

libavcodec/libavcodec.v

@@ -25,8 +25,6 @@ LIBAVCODEC_$MAJOR {
                 ff_mmxext_idct;
                 ff_idct_xvid*;
                 ff_jpeg_fdct*;
-                #XBMC's configure checks for ff_vdpau_vc1_decode_picture()
-                ff_vdpau_vc1_decode_picture;
                 ff_dnxhd_get_cid_table;
                 ff_dnxhd_cid_table;
         local:  *;