common: cope with i64::MIN in PartialOrd #247

Job	Run time
build (stable)	20s
build (beta)	22s
clippy	20s
build (nightly-2023-04-01)	26s
doc	19s
examples (stable)	22s
examples (beta)	21s
formatting	1m 0s
Rust 1.58.0 MSRV	1m 55s
examples (nightly-2023-04-01)	26s
Build for a no_std target (stable)	22s
Rust 1.59.0 MSRV	1m 20s
Build for a no_std target (beta)	19s
test (stable)	23s
Build for a no_std target (nightly-2023-04-01)	22s
udeps	4m 33s
test (beta)	22s
test (nightly-2023-04-01)	25s
coverage	13s
deny	3m 28s
	17m 38s

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