If cdr registration somehow succeeds without a config file, don't crash.

(closes issue #14563)
 Reported by: alerios


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.0@179360 65c4cc65-6c06-0410-ace0-fbb531ad65f3

cdr/cdr_sqlite3_custom.c

@@ -246,6 +246,11 @@ static int sqlite3_log(struct ast_cdr *cdr)
 	struct ast_channel dummy = { 0, };
 	int count = 0;
 
+	if (db == NULL) {
+		/* Should not be loaded, but be failsafe. */
+		return 0;
+	}
+
 	{ /* Make it obvious that only sql should be used outside of this block */
 		char *escaped;
 		char subst_buf[2048];