cdr_radius,cel_radius: Fix old memleak in unload

- Call "rc_openlog" optional. If you do not call,
you will simply NULL instead of a name.

- On the one PID can be only one syslog channel.
And it can already be run in logger.c

- Calling rc_openlog we assigns a new name for
the channel syslog. This unexpected behavior for logger.c.

Most lesser evil, is to agree on a NULL name syslog
if the channel was not launched in logger.c.

It also solves the problem of memory leaks.

ASTERISK-26455 #close

Change-Id: Ic17c38de67583e971d78fe18807d1a9faf8f0afd

cdr/cdr_radius.c

@@ -265,18 +265,6 @@ static int load_module(void)
 	} else
 		return AST_MODULE_LOAD_DECLINE;
 
-	/*
-	 * start logging
-	 *
-	 * NOTE: Yes this causes a slight memory leak if the module is
-	 * unloaded.  However, it is better than a crash if cdr_radius
-	 * and cel_radius are both loaded.
-	 */
-	tmp = ast_strdup("asterisk");
-	if (tmp) {
-		rc_openlog((char *) tmp);
-	}
-
 	/* read radiusclient-ng config file */
 	if (!(rh = rc_read_config(radiuscfg))) {
 		ast_log(LOG_NOTICE, "Cannot load radiusclient-ng configuration file %s.\n", radiuscfg);