feat: OFlag::O_SEARCH for apple targets (#2391) #1

Job	Run time
macos	3m 59s
macos-aarch64	2m 27s
linux_native_builds (x86_64-unknown-linux-gnu)	3m 15s
minver	14s
linux_native_builds (x86_64-unknown-linux-musl)	2m 52s
rust_stable	1m 16s
rustfmt	14s
tier3 (x86_64-unknown-dragonfly)	1m 1s
tier3 (x86_64-unknown-openbsd)	58s
tier3 (x86_64-unknown-haiku)	55s
cross_compiling	0s
redox	0s
cross	0s
	17m 11s

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