ISO9660 filesystem was updated to modern standards as of 20/11/2025.
The changes have - at the time of this writing - not been upstreamed.
Do compare (and port 'fs/iso9660' over) when updating the Buildroot release.

The following variables are filled in at build-time:
  - __EFI_ID_FILE__
  - __KERNEL_PATH__
  - __INITRD_PATH__ (automatically removed if not used)
