Add `io_uring_buf_ring` struct #4454

Job	Run time
Check nightly-only targets (nightly)	24s
Check --no-default-features (nightly)	59s
Check (stable)	6m 21s
Check selected Tier 3 platforms (nightly)	4m 57s
Check (nightly)	6m 14s
Check (1.63)	10m 21s
Rustfmt	4s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 2s
Test use-libc (ubuntu)	50s
Test rustix_use_experimental_asm (s390x-linux)	1m 27s
Test (ubuntu)	43s
Test use-libc (i686-linux)	53s
Test (ubuntu-20.04)	44s
Test use-libc (aarch64-linux)	1m 21s
Test (i686-linux)	59s
Test use-libc (powerpc64le-linux)	56s
Test (aarch64-linux)	1m 16s
Test use-libc (riscv64-linux)	1m 14s
Test (powerpc64le-linux)	1m 7s
Test use-libc (s390x-linux)	1m 5s
Test (riscv64-linux)	1m 3s
Test use-libc (arm-linux)	1m 21s
Test (s390x-linux)	59s
Test (arm-linux)	1m 10s
Test (ubuntu-stable)	46s
Test (i686-linux-stable)	1m 23s
Test (aarch64-linux-stable)	59s
Test (riscv64-linux-stable)	1m 8s
Test (s390x-linux-stable)	1m 5s
Test (powerpc64le-linux-stable)	1m 14s
Test (arm-linux-stable)	57s
Test (ubuntu-1.63)	2m 26s
Test (i686-linux-1.63)	2m 51s
Test (aarch64-linux-1.63)	3m 23s
Test (riscv64-linux-1.63)	2m 51s
Test (s390x-linux-1.63)	3m 1s
Test (powerpc64le-linux-1.63)	2m 45s
Test (arm-linux-1.63)	2m 51s
Test (macos-latest)	32s
Test (macos-13)	49s
Test (windows)	51s
Test (windows-2019)	1m 0s
Test (musl)	38s
	1h 19m 0s

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