Rust

Merge pull request #1578 from coreos/dependabot/cargo/libc-0.2.169 #2822

Job	Run time
Lints, pinned toolchain (x86_64)	58s
Docs	1m 0s
Lints, pinned toolchain (s390x)	1m 11s
Tests, minimum supported toolchain (x86_64)	1m 11s
Tests, unstable toolchain (beta, x86_64)	1m 1s
Tests, minimum supported toolchain (s390x)	1m 10s
Tests, stable toolchain (x86_64)	1m 8s
Tests, unstable toolchain (nightly, x86_64)	1m 11s
Tests, stable toolchain (s390x)	1m 11s
	10m 1s

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