ZSTDMT_sizeof_CCtx previously performed the complete size_t sum in C,
although every component depends on C-owned MT state and sizing helpers.
Keep the NULL guard, pool and dictionary queries, job-table multiplication,
and round-buffer extraction in C. Pass those eight computed components to a
Rust ABI helper that performs the same ordered wrapping additions.
This keeps MT context layout and allocator ownership on the C side while
moving only the scalar arithmetic across the existing C/Rust boundary.
Test Plan:
- `cargo clippy --manifest-path rust/Cargo.toml --no-default-features --features compression`
- Same clippy command with `--benches` and `--tests`, nightly fmt, then all three clippy commands again -- passed.
- `cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression` -- 289 passed.
- `make -B -C lib -j2 lib` -- passed.
- `make -C tests test-rust-lib-smoke` -- passed.
- `make -B -C tests -j2 fuzzer` and `tests/fuzzer -s4560 -t56 -i57 -v` -- passed.
- `make -C tests -j2 test-zstream` -- 84 named, 6,268, and 8,862 randomized cases passed.
- `git diff --check` and `git diff --cached --check` -- passed.
The zstream build retains its pre-existing unterminated-string warning at
`tests/zstreamtest.c:1899`.
ddidderr
efd3d76a4a