Fix setting O_NONBLOCK in parallel::stderr::set_non_blocking #1073

Job	Run time
Test CUDA support	22s
Test aarch64-apple-tvos	1m 48s
MSRV (ubuntu-latest)	20s
Clippy	25s
MSRV (windows-latest)	33s
Rustfmt	12s
Test (stable)	28s
Test (beta)	43s
Test (nightly)	34s
Test (linux32)	46s
Test (macos)	1m 22s
Test (aarch64-ios)	1m 1s
Test (win32)	1m 26s
Test (win64)	1m 30s
Test (mingw32)	1m 32s
Test (mingw64)	1m 25s
Test (windows-2019)	1m 31s
Test (windows-aarch64, windows-latest, stable, aarch64-pc-windows-msvc, --no-run)	1m 30s
	17m 28s

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