[0.2] Backport three pull requests

[tgross35]

Backport the following:

• adding new syscall id fchmodat2 for glibc/musl x86 (kernel >= 6.6). #3588
• Linux: add a new syscall SYS_mseal #3798
• Add missing NOTE_* constants to apple #3883

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[rustbot]

Some changes occurred in OpenBSD module

cc @semarie

Some changes occurred in solarish module

cc @jclulow, @pfmooney