Add AF_XDP syscalls, constants and types #3750

Job	Run time
Check --no-default-features (nightly)	54s
Check nightly-only targets (nightly)	22s
Rustfmt	7s
Check selected Tier 3 platforms (nightly)	3m 29s
Check (stable)	6m 6s
Check (nightly)	6m 14s
Test (ubuntu)	43s
Check (1.63)	10m 30s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 10s
Test (ubuntu-20.04)	43s
Test use-libc (ubuntu)	37s
Test (i686-linux)	1m 3s
Test use-libc (i686-linux)	57s
Test (aarch64-linux)	1m 4s
Test use-libc (aarch64-linux)	59s
Test (powerpc64le-linux)	1m 9s
Test use-libc (powerpc64le-linux)	1m 3s
Test (riscv64-linux)	1m 8s
Test use-libc (riscv64-linux)	1m 4s
Test (s390x-linux)	1m 4s
Test use-libc (arm-linux)	1m 25s
Test (arm-linux)	1m 5s
Test (ubuntu-stable)	34s
Test (i686-linux-stable)	1m 14s
Test (aarch64-linux-stable)	1m 10s
Test (riscv64-linux-stable)	1m 3s
Test (s390x-linux-stable)	1m 9s
Test (powerpc64le-linux-stable)	1m 3s
Test (arm-linux-stable)	1m 3s
Test (ubuntu-1.63)	2m 35s
Test (i686-linux-1.63)	2m 45s
Test (aarch64-linux-1.63)	3m 2s
Test (riscv64-linux-1.63)	2m 56s
Test (s390x-linux-1.63)	3m 2s
Test (powerpc64le-linux-1.63)	3m 2s
Test (arm-linux-1.63)	2m 48s
Test (macos-latest)	19m 15s
Test (macos-11)	1m 18s
Test (windows)	50s
Test (windows-2019)	47s
Test (musl)	38s
	1h 33m 10s

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