find_files(): don't sort files in my_dir(), sort table names

after all engines have discovered their tables
  
side effect: correct alphabetical sorting as in ORDER BY ... COLLATE utf8_bin,
information_schema is no longer the first after find_files(),
tables like #mysql50#zzz are sorted first (as per table name),
not last (as per file name zzz).

mysql-test/r/mysqlcheck.result

@@ -176,15 +176,15 @@ t1
 v1
 show tables;
 Tables_in_test
-t1
 #mysql50#v-1
+t1
 v1
 test.t1                                            OK
 show tables;
 Tables_in_test
 t1
-v1
 v-1
+v1
 drop view v1, `v-1`;
 drop table t1;
 SET NAMES utf8;