journal: set flushed flag even if we fail to open runtime journals

As at this stage, a persistent journal file has been already opened, and
saved seqnum has been reset, and any later journal entries will be stored
to the file. Hence we should not open the runtime journal file by
server_system_journal_open() again.

src/journal/journald-server.c

@@ -1347,9 +1347,10 @@ int server_flush_to_var(Server *s, bool require_flag_file) {
         start = now(CLOCK_MONOTONIC);
 
         r = sd_journal_open(&j, SD_JOURNAL_RUNTIME_ONLY | SD_JOURNAL_ASSUME_IMMUTABLE);
-        if (r < 0)
-                return log_ratelimit_error_errno(r, JOURNAL_LOG_RATELIMIT,
-                                                 "Failed to read runtime journal: %m");
+        if (r < 0) {
+                log_ratelimit_error_errno(r, JOURNAL_LOG_RATELIMIT, "Failed to read runtime journal: %m");
+                goto finish;
+        }
 
         sd_journal_set_data_threshold(j, 0);