Re: [PATCH 0/3] treewide: migrate from legacy utime.h to utimensat

"Alexey Samsonov via GitGitGadget" [off-list ref] writes:

utime() function for setting access/modification time for files (and a
corresponding <utime.h> header) have been officially removed from POSIX
starting from POSIX.1-2024. While existing system library implementations
still provide this function for compatibility reasons, its implementation
may be removed in the future, or otherwise degrade over time. Some newer
libc implementations (e.g. LLVM-libc, currently under development) don't
provide utime() function at all.

This PR switches the git codebase to recommended alternative: utimensat()
POSIX function (which supports nanosecond-level precision) from <fcntl.h>,
and, as a possible fallback for older systems compatibility, utimes()
function from <sys/stat.h>. It also provides the corresponding MinGW
wrapper.

The alternative is to unconditionally use utimes() where possible, but given
that utimensat is available in glibc starting from 2007, and on BSD systems
since 2012 or so, it makes sense to use the newer variant by default.

I hear that Apple has supported it since macOS 10.13 High Sierra,
which came out in 2017 and reached EOL in 2020, so we should be safe
there as well.