ZSTD_sizeof_localDict only combines the optional local dictionary buffer
size with the already-owned C dictionary size. Keep dictionary ownership and
workspace sizing in C, but pass the three scalar inputs to Rust so the leaf
uses explicit C size_t wrapping semantics. The CCtx NULL sizing guard and
surrounding ownership and call structure remain unchanged.
Test Plan:
- `cargo clippy --manifest-path rust/Cargo.toml --no-default-features --features compression` (before and after formatting) -- passed
- The same clippy command with `--benches` and `--tests` (before and after formatting) -- passed
- `cargo +nightly fmt --manifest-path rust/Cargo.toml` -- passed
- `cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression` -- 272 passed
- `make -B -C lib -j2 lib` -- passed
- `make -C tests test-rust-lib-smoke` and direct `rustLibSmoke` execution -- passed
- `make -C tests -j2 fuzzer` -- passed
- `./fuzzer -s4560 -t56 -i57 -v` -- passed
- `git diff --check` and `git diff --cached --check` -- passed
ddidderr
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