* gnu/services/configuration.scm (id): New procedure extracted from
define-configuration.
(define-maybe): New exported procedure, moved from messaging.scm.
* gnu/services/messaging.scm (define-maybe): Remove it.
(id): Move declaration inside define-all-configurations which is now
the only caller procedure.
Signed-off-by: Clément Lassieur <clement@lassieur.org>
* gnu/services/messaging.scm (define-all-configurations): Use 'id' to
introduce raw/literal/unhygienic top-level identifiers. Fixes
compilation with Guile 2.2.
