Package systemd-boot-efi: Information

- Fix compatibility with packages which install files outside %_prefix, IOW,
  in the legacy unmerged-usr locations. (thanks to sin@)

- 255.6
- Migrate from /lib to /usr/lib (usrmerge).
- Build with p11kit and fido2 support.

- Adapted the package for filesystem >= 3:
  + put /bin after /usr/bin in default PATH for spawned processes;
  + fix symlink targets which were relative for standalone legacy directories.
  This makes us incompatible with filesystem < 3.
  See https://altlinux.org/Usrmerge for more information.