proposal: x/sys/unix: add `STATX_MNT_ID_UNIQUE` mask value

[Jorropo]

Proposal Details

98d2b43081972abeb5bb5a087bc3e3197531c46e released in linux 6.8 added a new mask option for unix.Statx STATX_MNT_ID_UNIQUE which fills in the field Statx_t.Mnt_id with a monotonic mount id (instead of STATX_MNT_ID which are reused).

So add:

const STATX_MNT_ID_UNIQUE = 0x4000

[Jorropo]

Nvm this was added in 27dc90bcf4d797251506d82bd56307ca2c13d59c but this is yet to be released.