Add NOEXEC_SEAL and EXEC to MemfdFlags #3728

Job	Run time
Check nightly-only targets (nightly)	23s
Rustfmt	12s
Check --no-default-features (nightly)	54s
Check selected Tier 3 platforms (nightly)	1m 52s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 16s
Test (ubuntu)	47s
Test use-libc (ubuntu)	41s
Test (ubuntu-20.04)	41s
Check (stable)	2m 53s
Test use-libc (i686-linux)	1m 13s
Test (i686-linux)	1m 5s
Test use-libc (aarch64-linux)	1m 43s
Check (nightly)	2m 54s
Test (aarch64-linux)	1m 18s
Test use-libc (powerpc64le-linux)	59s
Check (1.63)	3m 12s
Test (powerpc64le-linux)	1m 14s
Test use-libc (riscv64-linux)	1m 33s
Test (riscv64-linux)	1m 6s
Test use-libc (arm-linux)	1m 12s
Test (s390x-linux)	1m 27s
Test (arm-linux)	1m 6s
Test (ubuntu-stable)	39s
Test (i686-linux-stable)	1m 10s
Test (aarch64-linux-stable)	1m 13s
Test (riscv64-linux-stable)	1m 3s
Test (s390x-linux-stable)	1m 2s
Test (powerpc64le-linux-stable)	1m 16s
Test (arm-linux-stable)	1m 3s
Test (ubuntu-1.63)	2m 0s
Test (i686-linux-1.63)	2m 40s
Test (aarch64-linux-1.63)	2m 14s
Test (riscv64-linux-1.63)	2m 35s
Test (s390x-linux-1.63)	2m 12s
Test (powerpc64le-linux-1.63)	2m 13s
Test (arm-linux-1.63)	2m 37s
Test (macos-latest)	19m 7s
Test (macos-11)	1m 10s
Test (windows)	48s
Test (windows-2019)	56s
Test (musl)	39s
	1h 16m 18s

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