Do not raise an exception at gcroot directory creation.

On fresh Guix System installations, Cuirass will not be allowd to create its
own profile directory. Instead this should be take care of by guix-daemon when
Cuirass will initiate its first connection to it.

* bin/cuirass.in (main): Do not raise an exception on gcroot directory
creation failure.

bin/cuirass.in

@@ -112,7 +112,9 @@ exec ${GUILE:-@GUILE@} --no-auto-compile -e main -s "$0" "$@"
         (show-version)
         (exit 0))
        (else
-        (mkdir-p (%gc-root-directory))
+        ;; If we cannot create the gcroot directory, it should be done later
+        ;; on by guix-daemon itself.
+        (false-if-exception (mkdir-p (%gc-root-directory)))
         (let ((one-shot? (option-ref opts 'one-shot #f))
               (port (string->number (option-ref opts 'port "8080")))
               (host (option-ref opts 'listen "localhost"))