Flags for fchmodat()

There as a discussion a few years back when we did openat2(), clone3() and others that simple versioning is the default.
In sheer numbers this scheme also wins iirc.

There's also the possibility that a system call like bla4() is broken and you'd wanted to change a system call argument type but not the actual number of arguments. Then you'd not be able to call it bla5() and blat4.2() would be rather weird. Imho, the simple versioning is just more flexible and is nowadays the de facto standard anyway.

I also had documentation for all of this but there was never enough time to send it actually but fwiw:

https://github.com/brauner/linux/commit/5fe619ce62bae64cf...

which is part of

https://github.com/brauner/linux/commits/docs_extensible_...

and contains a lot of other info.