system: Allow 'chfn' to change the user's full name....Fixes <https://issues.guix.gnu.org/52539>.
Reported by Jacob First <jacob.first@member.fsf.org>.
* gnu/build/accounts.scm (allocate-passwd): Add comment as to why
'real-name' is taken from PREVIOUS. Add (not system?) to the
condition.
* gnu/system.scm (operating-system-etc-service) <login.defs>: Add
"CHFN_RESTRICT".
* gnu/system.scm (%setuid-programs): Add "chfn".
* gnu/system/pam.scm (base-pam-services): Add "chfn".
* doc/guix.texi (User Accounts): Document it.