From vaptvupt-codec tag v2.65.3. Output is byte-identical to 2.65.0 (same
ratio, wire format v1.6 unchanged) but extreme-mode encode is ~1.6-2x faster
(Sprint 132 optimal-parser speedup) and the extreme prepass window allocation
is capped at wlog=20 = 8 MiB virtual instead of up to 128 MiB (Sprint 133
memory hygiene). Our AVX2 offset-read decoder guard is now UPSTREAM (dropped
from the local patch set); the ANS safe-zone 2*SAFEZONE_MAX_RUN reserve is
re-applied on top (still not upstream). make check 16/16, KAT 16/16, cross-
version roundtrip with 5.1.0 archives verified.
59f9ebc59e