journal: Don't immediately flush output events to disk

Commit 478566258 'New journal event "output"' (v4.3.27) claims "Output
events are *not* flushed to disk immediately."  They are.  Accident.
Implement the missing bit.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

src/lib/subs/journal.c

@@ -128,6 +128,7 @@ journal_entry_end(int newline, int flush)
     if (!newline)
 	fputc('\\', journal);
     fputc('\n', journal);
+    if (flush)
 	fflush(journal);
     if (ferror(journal)) {
 	logerror("Error writing journal (%s)", strerror(errno));