cmp: stop allocating for byte printing #20

Job	Run time
cargo fmt --all -- --check	8s
cargo clippy -- -D warnings (windows-latest)	47s
cargo check (ubuntu-latest)	14s
cargo test (windows-latest)	5m 44s
cargo check (windows-latest)	41s
cargo check (macOS-latest)	15s
cargo test (macOS-latest)	1m 29s
GNU test suite	54s
Code Coverage (ubuntu-latest, unix)	1m 54s
Code Coverage (macos-latest, macos)	3m 19s
Code Coverage (windows-latest, windows)	6m 20s
cargo clippy -- -D warnings (macOS-latest)	16s
cargo test (ubuntu-latest)	30s
cargo clippy -- -D warnings (ubuntu-latest)	16s
	22m 47s

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