A syscall for changing birth time

[Artem S. Tashkinov]

Hello,

Why is it that the Linux kernel supports reading btime, but there's no
syscall to change it? At least for ext4 there's the debugfs utility, but
for other filesystems there's just nothing. And even debugfs is not a
solution, since it requires root privileges and an unmounted/mounted RO
filesystem.

Having it allows for better compatibility with Windows and BSD operating
systems and could improve backup/restore.

Best regards,
Artem