Log Message:
dav1d: update to 1.2.0.

Changes for 1.2.0 'Arctic Peregrine Falcon':
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1.2.0 is a small release of dav1d, adding more SIMD and fixes

- Improvements on attachments of props and T.35 entries on output pictures
- NEON z1/z3 high bit-depth optimizations and improvements for 8bpc
- SSSE3 z2/z3 8bpc and SSSE3 z1/z3 high bit-depth optimziations
- refmvs.save_tmvs optimizations in SSSE3/AVX2/AVX-512
- AVX-512 optimizations for high bit-depth itx (16x64, 32x64, 64x16, 64x32, 64x64)
- AVX2 optimizations for 12bpc for 16x32, 32x16, 32x32 itx