Speed up emit_dist with precomputed length codings for static trees #1087

Job	Run time
QEMU build & test (stable, ubuntu-latest, s390x-unknown-linux-gnu, s390x-linux-gnu-gcc)	43s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-gnu)	56s
cargo-c dynamic library	9s
QEMU build & test (stable, ubuntu-latest, i686-unknown-linux-gnu, i686-linux-gnu-gcc)	40s
Build and test (msrv, ubuntu-latest, x86_64-unknown-linux-gnu)	1m 6s
Build and test (beta, ubuntu-latest, x86_64-unknown-linux-gnu)	59s
Build and test (stable, macos-latest, x86_64-apple-darwin)	1m 1s
Smoke-test fuzzing targets (default)	2m 37s
Smoke-test fuzzing targets (stable, macos-14, aarch64-apple-darwin)	2m 21s
Smoke-test fuzzing targets (c-allocator)	2m 34s
Build and test (stable, macos-14, aarch64-apple-darwin)	54s
Clippy	1m 22s
Build and test (stable-x86_64-gnu, windows-2022, x86_64-pc-windows-gnu)	2m 30s
Smoke-test fuzzing targets (rust-allocator)	2m 40s
Clippy (--no-default-features --features="c-allocator")	22s
vanilla dynamic library	13s
Clippy (--no-default-features --features="rust-allocator")	17s
Miri	1m 45s
run flate2 test suite	18s
wasm32	39s
	24m 6s

Provide feedback