polkit_subject_to_string() is called inside the HAVE_LIBSYSTEMD guard
in flatpak_dir_log(), but <polkit/polkit.h> is only included when
USE_SYSTEM_HELPER is defined. This causes a build failure on
configurations that have libsystemd but no system helper.
Guard the polkit call with USE_SYSTEM_HELPER and fall back to "(none)"
so the subject string is always valid for the sd_journal_send() call.
Fixes: f9d5c5c ("dir: Free result of polkit_subject_to_string")
Signed-off-by: Rudi Heitbaum <rudi@heitbaum.com>
68ffa487ee