compat_linux: open: Supporting O_NOATIME

[Aiman Najjar <aiman.najjar%hurranet.com@localhost>]

Hello tech-kern,

I'm new to NetBSD and I am interested in contributing to compat_linux.

I've had a chance to look at the work Henrique did for the LTP as part 
of GSoC, I am interested in working on some of the failing test cases.

In particular, `open02` test case seems like a good candidate for a 
first patch. The failing test case passes `O_NOATIME` mode flag to open, 
and expects it to fail with `EPERM` error.

My question: what is the correct way to address this, do we: 1) add 
native support for `O_NOATIME`, which allows users to flag (or hint) 
that they don't want the file's access time to be updated (useful for 
backup solutions processing large amount of files), or 2) do we emulate 
it, somehow, at `compat_linux` layer (e.g. only support this behavior 
when the module is installed) or 3) Do we only check for user privileges 
(which would make the test pass) but do not actually implement the behavior?

Additionally, re. privilege check: Linux checks the privilege by 
ensuring process effective UID matches the file owner UID, or if the 
process has `CAP_FOWNER` [*]. On NetBSD, I presume we'd only do the 
first check?

Also, stumbled upon a similar discussion in FreeBSD forums: 
https://forums.freebsd.org/threads/o_noatime-option-in-open.92523/

Thanks,
Aiman

[*] 
https://manpages.debian.org/trixie/manpages-dev/openat.2.en.html#O_NOATIME