MkOrigtargz.pm: dump newline to same output as messages

Forward the final newline to the same output the previous messages are send to. Otherwise it might get lost, e.g. by gbp:

$ gbp import-orig --uscan
gbp:info: Launching uscan...
Newest version of nextcloud-desktop on remote site is 3.10.1, local version is 3.10.0
 => Newer package available from:
        => https://github.com/nextcloud/desktop/archive/refs/tags/v3.10.1.tar.gz
Leaving ../nextcloud-desktop_3.10.1.orig.tar.gz where it isgbp:info: Using uscan downloaded tarball ../nextcloud-desktop_3.10.1.orig.tar.gz