Linux fallout from the hoist the mac could not see: bindgen emits unsafe
blocks (layout tests/accessors) into OUT_DIR, where nobody hand-writes
SAFETY proofs — pyrowave-sys failed clippy on .25 with 17 of them, and
libvpl-sys would do the same on the Windows leg. Both crates are
bindings-only by charter (the safe wrapper lives with the consumer), so the
allow is crate-wide with the rationale at the crate root; the hand-written
link-sanity tests keep their proofs by convention.