cmp: fix 32-bit usize overflow in test (#173) #615

Job	Run time
cargo check (macOS-latest)	13s
GNU test suite	46s
cargo test (windows-latest)	4m 50s
cargo test (ubuntu-latest)	50s
cargo check (ubuntu-latest)	13s
cargo test (macOS-latest)	1m 35s
cargo fmt --all -- --check	8s
cargo clippy -- -D warnings (ubuntu-latest)	20s
Code Coverage (macos-latest, macos)	3m 40s
Code Coverage (windows-latest, windows)	6m 58s
cargo check (windows-latest)	43s
cargo clippy -- -D warnings (macOS-latest)	13s
cargo clippy -- -D warnings (windows-latest)	38s
Code Coverage (ubuntu-latest, unix)	1m 57s
	23m 4s

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