Fix server not to create a journal on SIGHUP when !keep_journal:

(journal_reopen): New.
(main): Use it.  Fixes failure to obey !keep_journal.
(journal_open): Internal linkage, changed semantics and return value.
Callers changed.
(journal_close): One caller left, inline and remove.

src/server/main.c

@@ -267,8 +267,7 @@ main(int argc, char **argv)
 	sig = empth_wait_for_signal();
 #ifdef SIGHUP
 	if (sig == SIGHUP) {
-	    journal_close();
-	    journal_open();
+	    journal_reopen();
 	    continue;
 	}
 #endif