Add simple interface for busy_poll on Linux #1350

Job	Run time
Clippy	19s
Rustfmt	10s
Test (nightly)	20s
Test (beta)	26s
Test (stable)	23s
Test (1.70.0)	25s
Test (macos)	23s
check-external-types (macos-latest)	19s
Test (windows)	51s
check-external-types (windows-latest)	35s
check-external-types (ubuntu-latest)	18s
Check (aarch64-apple-ios)	34s
Check (aarch64-apple-tvos)	33s
Check (aarch64-apple-darwin)	35s
Check (aarch64-unknown-linux-musl)	35s
Check (aarch64-unknown-freebsd)	31s
Check (aarch64-unknown-linux-ohos)	42s
Check (aarch64-unknown-openbsd)	33s
Check (aarch64-linux-android)	32s
Check (aarch64-apple-watchos)	34s
Check (arm-linux-androideabi)	34s
Check (aarch64-unknown-netbsd)	34s
Check (armv7-linux-androideabi)	31s
Check (arm64_32-apple-watchos)	34s
Check (armv7-sony-vita-newlibeabihf)	34s
Check (aarch64-unknown-linux-gnu)	36s
Check (aarch64-unknown-redox)	34s
Check (x86_64-apple-darwin)	33s
Check (i686-linux-android)	35s
Check (sparcv9-sun-solaris)	35s
Check (x86_64-pc-solaris)	35s
Check (armv7-unknown-linux-ohos)	33s
Check (i686-unknown-linux-gnu)	32s
Check (x86_64-unknown-illumos)	39s
Check (x86_64-unknown-fuchsia)	36s
Check (x86_64-pc-windows-msvc)	33s
Check (x86_64-unknown-freebsd)	39s
Check (x86_64-pc-cygwin)	35s
Check (x86_64-apple-ios)	34s
Check (x86_64-unknown-linux-gnu)	33s
Check (x86_64-unknown-dragonfly)	34s
Check (x86_64-unknown-linux-musl)	34s
Check (x86_64-unknown-linux-ohos)	37s
Check (x86_64-unknown-netbsd)	35s
Check (x86_64-unknown-openbsd)	32s
Check (x86_64-unknown-redox)	37s
	24m 36s

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