unistd: adding linux(glibc)/freebsd close_range. #1559

Job	Run time
macos-aarch64	2m 42s
macos	4m 49s
minver	16s
linux_native_builds (x86_64-unknown-linux-gnu)	3m 16s
rust_stable	28s
rustfmt	6s
linux_native_builds (x86_64-unknown-linux-musl)	3m 17s
tier3 (x86_64-unknown-dragonfly)	1m 1s
tier3 (x86_64-unknown-openbsd)	57s
tier3 (x86_64-unknown-haiku)	58s
tier3 (armv7-unknown-linux-uclibceabihf)	1m 11s
tier3 (i686-unknown-hurd-gnu)	1m 12s
cross_compiling	0s
redox	0s
cross	0s
	20m 13s

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