Use more constants and functions from libc (#368) #203

Job	Run time
aarch64-apple-darwin	52s
aarch64-apple-darwin force-inprocess	41s
aarch64-apple-darwin async	55s
x86_64-apple-darwin	1m 33s
x86_64-apple-darwin force-inprocess	1m 23s
x86_64-apple-darwin async	1m 40s
x86_64-unknown-linux-gnu	57s
x86_64-unknown-linux-gnu force-inprocess	55s
x86_64-unknown-linux-gnu async	58s
x86_64-pc-windows-msvc	3m 10s
x86_64-pc-windows-msvc force-inprocess	2m 58s
x86_64-pc-windows-msvc async	2m 54s
i686-pc-windows-msvc	3m 38s
i686-pc-windows-msvc force-inprocess	3m 5s
i686-pc-windows-msvc async	2m 28s
x86_64-unknown-linux-gnu memfd	59s
Result	1s
	29m 7s

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