Speed up emit_dist with precomputed length codings for static trees #1086

Job	Run time
cargo-c dynamic library	9s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-gnu)	53s
QEMU build & test (stable, ubuntu-latest, s390x-unknown-linux-gnu, s390x-linux-gnu-gcc)	40s
Build and test (msrv, ubuntu-latest, x86_64-unknown-linux-gnu)	1m 1s
Clippy	21s
QEMU build & test (stable, ubuntu-latest, i686-unknown-linux-gnu, i686-linux-gnu-gcc)	35s
Build and test (beta, ubuntu-latest, x86_64-unknown-linux-gnu)	59s
Clippy (--no-default-features --features="c-allocator")	24s
Smoke-test fuzzing targets (default)	2m 29s
Build and test (stable, macos-latest, x86_64-apple-darwin)	1m 3s
Clippy (--no-default-features --features="rust-allocator")	19s
Smoke-test fuzzing targets (c-allocator)	2m 31s
Smoke-test fuzzing targets (stable, macos-14, aarch64-apple-darwin)	2m 26s
Build and test (stable, macos-14, aarch64-apple-darwin)	53s
Smoke-test fuzzing targets (rust-allocator)	2m 32s
Build and test (stable-x86_64-gnu, windows-2022, x86_64-pc-windows-gnu)	1m 55s
vanilla dynamic library	14s
Miri	1m 49s
run flate2 test suite	37s
wasm32	36s
	22m 26s

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