Changes for 1.5.0 'Sonic':

1.5.0 is a major release of dav1d, that:

• WARNING: we removed some of the SSE2 optimizations, so if you care about systems without SSSE3, you should be careful when updating!
• Add Arm OpenBSD run-time CPU feature
• Optimize index offset calculations for decode_coefs
• picture: copy HDR10+ and T35 metadata only to visible frames
• SSSE3 new optimizations for 6-tap (8bit and hbd)
• AArch64/SVE: Add HBD subpel filters using 128-bit SVE2
• AArch64: Add USMMLA implempentation for 6-tap H/HV
• AArch64: Optimize Armv8.0 NEON for HBD horizontal filters and 6-tap filters
• Power9: Optimized ITX till 16x4.
• Loongarch: numerous optimizations
• RISC-V optimizations for pal, cdef_filter, ipred, mc_blend, mc_bdir, itx
• Allow playing videos in full-screen mode in dav1dplay