When invoking `cl -?`, set stdin to null #2022

Job	Run time
Test wasm32-wasip1-thread	1m 5s
Test wasm (wasm32-unknown-unknown)	10s
Clippy	26s
Test build-std (aarch64-tvos)	3m 8s
Test CUDA support	33s
Test build-std (aarch64-tvos-sim)	2m 17s
MSRV (ubuntu-latest)	21s
Test build-std (x86_64-tvos)	2m 26s
MSRV (windows-latest)	40s
Rustfmt	13s
MSRV (macos-latest)	29s
semver-checks	2m 39s
Test (stable)	1m 49s
Test (beta)	1m 27s
Test (nightly)	1m 54s
Test (linux32)	2m 8s
Test (macos)	4m 36s
Test (aarch64-macos)	2m 26s
Test (aarch64-ios)	1m 46s
Test (win32)	3m 7s
Test (win64)	2m 58s
Test (mingw32)	3m 4s
Test (mingw64)	3m 19s
Test (windows-2019)	4m 2s
Test (windows-aarch64, windows-latest, stable, aarch64-pc-windows-msvc, --no-run)	2m 58s
Test (windows-clang, windows-2019, stable, x86_64-pc-windows-msvc, clang, clang++)	4m 9s
Test (windows-clang-cl, windows-2019, stable, x86_64-pc-windows-msvc, clang-cl, clang-cl)	7m 52s
	1h 2m 2s

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