avoid use of uninitilized ref frames in parse_frame_hdr
Fixes a NULL derefence with clusterfuzz-testcase-minimized-dav1d_fuzzer-5724731362246656. Credits to oss-fuzz.
Fixes a NULL derefence with clusterfuzz-testcase-minimized-dav1d_fuzzer-5724731362246656. Credits to oss-fuzz.
VideoLAN code repository instance