Fix clippy warnings #1688

Job	Run time
Test build-std (aarch64-tvos)	1m 32s
Test build-std (aarch64-tvos-sim)	1m 34s
Test CUDA support	32s
Clippy	8s
Test build-std (x86_64-tvos)	1m 35s
MSRV (ubuntu-latest)	20s
Rustfmt	10s
semver-checks	16s
MSRV (windows-latest)	40s
Test (stable)	26s
Test (beta)	30s
Test (nightly)	26s
Test (linux32)	1m 28s
Test (macos)	2m 50s
Test (aarch64-macos)	1m 14s
Test (aarch64-ios)	30s
Test (win32)	1m 13s
Test (win64)	2m 54s
Test (mingw32)	1m 50s
Test (mingw64)	1m 48s
Test (windows-2019)	1m 42s
Test (windows-aarch64, windows-latest, stable, aarch64-pc-windows-msvc, --no-run)	2m 24s
Test (windows-clang, windows-2019, stable, x86_64-pc-windows-msvc, clang, clang++)	2m 15s
Test (windows-clang-cl, windows-2019, stable, x86_64-pc-windows-msvc, clang-cl, clang-cl)	1m 53s
	30m 10s

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