cmp: stop allocating for byte printing #19

Job	Run time
GNU test suite	1m 2s
cargo fmt --all -- --check	6s
cargo clippy -- -D warnings (ubuntu-latest)	10s
Code Coverage (ubuntu-latest, unix)	1m 56s
Code Coverage (windows-latest, windows)	6m 28s
cargo clippy -- -D warnings (macOS-latest)	13s
cargo clippy -- -D warnings (windows-latest)	49s
Code Coverage (macos-latest, macos)	2m 31s
cargo test (ubuntu-latest)	35s
cargo test (windows-latest)	4m 37s
cargo check (ubuntu-latest)	14s
cargo test (macOS-latest)	1m 39s
cargo check (windows-latest)	46s
cargo check (macOS-latest)	15s
	21m 21s

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