Fix nondeterministic failure of innodb.table_flags

The files ibtmp1 and ib_buffer_pool are sometimes created, sometimes not.
Remove them if they exist.

mysql-test/suite/innodb/r/table_flags.result

@@ -174,7 +174,6 @@ a
 SELECT * FROM tp;
 a
 DROP TABLE tr,tc,td,tz,tp;
-ib_buffer_pool
 ib_logfile0
 ib_logfile1
 ibdata1

mysql-test/suite/innodb/t/table_flags.test

@@ -194,6 +194,11 @@ DROP TABLE tr,tc,td,tz,tp;
 --let $restart_parameters=
 --source include/restart_mysqld.inc
 
+--error 0,1
+--remove_file $bugdir/ibtmp1
+--error 0,1
+--remove_file $bugdir/ib_buffer_pool
+
 --list_files $bugdir
 --remove_files_wildcard $bugdir
 --rmdir $bugdir