obu: check refresh_frame_flags is not equal to allFrames on Intra Only frames (!1411) · Merge requests · VideoLAN / dav1d

From section 6.8.2 in the AV1 spec:

"If frame_type is equal to INTRA_ONLY_FRAME, it is a requirement of bitstream conformance that refresh_frame_flags is not equal to 0xff."

Make this a soft requirement by checking that strict standard complaince is enabled.

obu: check refresh_frame_flags is not equal to allFrames on Intra Only frames