Add reboot syscall #3264

Job	Run time
Rustfmt	16s
Check (stable)	3m 8s
Check nightly-only targets (nightly)	32s
Check (nightly)	3m 4s
Check (1.63)	3m 21s
Check --no-default-features (nightly)	1m 26s
Check selected Tier 3 platforms (nightly)	42s
Test (ubuntu)	1m 3s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 36s
Test (ubuntu-20.04)	1m 3s
Test use-libc (ubuntu)	1m 8s
Test (i686-linux)	1m 14s
Test use-libc (i686-linux)	1m 58s
Test (aarch64-linux)	1m 19s
Test use-libc (aarch64-linux)	1m 58s
Test (powerpc64le-linux)	1m 14s
Test use-libc (powerpc64le-linux)	2m 4s
Test (riscv64-linux)	1m 16s
Test use-libc (riscv64-linux)	1m 47s
Test (s390x-linux)	1m 15s
Test use-libc (arm-linux)	1m 36s
Test (arm-linux)	1m 19s
Test (ubuntu-stable)	1m 15s
Test (i686-linux-stable)	1m 21s
Test (aarch64-linux-stable)	1m 16s
Test (riscv64-linux-stable)	1m 3s
Test (s390x-linux-stable)	1m 15s
Test (powerpc64le-linux-stable)	1m 16s
Test (arm-linux-stable)	1m 18s
Test (ubuntu-1.63)	1m 18s
Test (i686-linux-1.63)	1m 16s
Test (aarch64-linux-1.63)	1m 18s
Test (riscv64-linux-1.63)	1m 14s
Test (s390x-linux-1.63)	1m 16s
Test (powerpc64le-linux-1.63)	1m 15s
Test (arm-linux-1.63)	1m 18s
Test (macos-latest)	54s
Test (macos-11)	56s
Test (windows)	1m 3s
Test (windows-2019)	1m 3s
	55m 54s

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