chore(deps): update rust crate libc to v0.2.168 #593

Job	Run time
cargo check (ubuntu-latest)	23s
cargo clippy -- -D warnings (ubuntu-latest)	21s
Code Coverage (ubuntu-latest, unix)	1m 58s
cargo clippy -- -D warnings (macOS-latest)	55s
Code Coverage (macos-latest, macos)	1m 46s
Code Coverage (windows-latest, windows)	4m 9s
cargo clippy -- -D warnings (windows-latest)	2m 7s
cargo check (macOS-latest)	19s
cargo check (windows-latest)	2m 46s
cargo test (ubuntu-latest)	31s
cargo fmt --all -- --check	8s
cargo test (macOS-latest)	28s
cargo test (windows-latest)	2m 15s
	18m 6s

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