TODO: Use STATX_BTIME in addition to inode number

[rfjakob]

Linux 4.11 gained statx: https://man7.org/linux/man-pages/man2/statx.2.html

This solves the problem of inode number recycling, which was the reason for -sharedstorage.

In my testing, STATX_BTIME (birth time) works on NFS and also CIFS. It is reported by recent versions of stat.

An alternative may be FS_IOC_GETVERSION ( https://stackoverflow.com/a/28006048/1380267 ), but this is harder to get (needs an IOCTL), and I don't know if it works on NFS or CIFS.