syscalls: Avoid C++ reserved words

[des]

Summary

Both kern_renameat() and kern_dup() had arguments named new. Rename
their arguments to match their respecitve manual pages.

Sponsored by: Klara, Inc.
Sponsored by: NetApp, Inc.

[kib]

sys/kern/kern_descrip.c

1043

Usually we use suffix 'fd' for something that is file descriptor. Why not name the args oldfd and newfd?

You already used the the pattern for other chunks in the diff.

[des]

sys/kern/kern_descrip.c

1043

The answer is in the commit message.

[kib]

sys/kern/kern_descrip.c

1043

Man page is for userspace, there we are in kernel and it would be better to follow the in-kernel naming conventions than userspace man page.

But do a you want.

[des]

sys/kern/kern_descrip.c

1043

It seemed preferable to pick names for which there was precedent _somewhere_ rather than make up my own.

I would like to point out, though, that unlike renameat(2), dup(2) is not only used for files, so fd does not seem appropriate.

[kib]

sys/kern/kern_descrip.c

1043

Yes, and I point to the dup(2) man page to be outlier instead of the kernel parameters name.
Unix tradition is to name descriptor indexes 'file descriptors', whatever they point to (they always point to struct file in kernel FWIW).