cdylib cleanup #1051

Job	Run time
QEMU build & test (stable, ubuntu-latest, s390x-unknown-linux-gnu, s390x-linux-gnu-gcc)	51s
Clippy	18s
QEMU build & test (stable, ubuntu-latest, i686-unknown-linux-gnu, i686-linux-gnu-gcc)	45s
cargo-c dynamic library	18s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-gnu)	1m 0s
Clippy (--no-default-features --features="c-allocator")	22s
Build and test (msrv, ubuntu-latest, x86_64-unknown-linux-gnu)	1m 0s
Clippy (--no-default-features --features="rust-allocator")	18s
Smoke-test fuzzing targets (default)	2m 39s
Build and test (beta, ubuntu-latest, x86_64-unknown-linux-gnu)	57s
Smoke-test fuzzing targets (c-allocator)	2m 36s
Build and test (stable, macos-latest, x86_64-apple-darwin)	1m 27s
Smoke-test fuzzing targets (rust-allocator)	2m 33s
Build and test (stable, macos-14, aarch64-apple-darwin)	1m 9s
Smoke-test fuzzing targets (stable, macos-14, aarch64-apple-darwin)	2m 55s
vanilla dynamic library	20s
Build and test (stable-x86_64-gnu, windows-2022, x86_64-pc-windows-gnu)	2m 19s
Miri	1m 39s
wasm32	42s
run flate2 test suite	22s
	24m 30s

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