vc1parse: parse frame header when stream format is ASF/raw for simple/main profile
When stream-format is ASF or sequence-layer-raw-frame, we basically have a raw frame so we can parse it to extract some information such the keyframe flag. The only requirement is to have a valid sequence-header. This commit parse the frame header and set the DELTA_UNIT buffer flag in case the frame is not a keyframe. https://bugzilla.gnome.org/show_bug.cgi?id=738519