`fn len_and_friends`: return `ControlFlow` instead of `Option` #1070

Job	Run time
QEMU build & test (stable, ubuntu-latest, s390x-unknown-linux-gnu, s390x-linux-gnu-gcc)	49s
Clippy	32s
cargo-c dynamic library	20s
QEMU build & test (stable, ubuntu-latest, i686-unknown-linux-gnu, i686-linux-gnu-gcc)	43s
Clippy (--no-default-features --features="c-allocator")	19s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-gnu)	58s
Clippy (--no-default-features --features="rust-allocator")	19s
Build and test (msrv, ubuntu-latest, x86_64-unknown-linux-gnu)	1m 22s
Build and test (beta, ubuntu-latest, x86_64-unknown-linux-gnu)	1m 0s
Build and test (stable, macos-latest, x86_64-apple-darwin)	1m 19s
Smoke-test fuzzing targets (stable, macos-14, aarch64-apple-darwin)	2m 34s
Smoke-test fuzzing targets (default)	2m 33s
Build and test (stable, macos-14, aarch64-apple-darwin)	1m 9s
vanilla dynamic library	21s
Smoke-test fuzzing targets (c-allocator)	2m 35s
Build and test (stable-x86_64-gnu, windows-2022, x86_64-pc-windows-gnu)	2m 8s
Smoke-test fuzzing targets (rust-allocator)	2m 37s
Miri	1m 43s
run flate2 test suite	18s
wasm32	36s
	24m 15s

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