mysql5.1: make buildable but alter_table_disable_enable_keys still fails
mysql5.1: make buildable but alter_table_disable_enable_keys still fails

refs #1310 #1311

yoku0825/mroonga,yoku0825/mroonga,mroonga/mroonga,naoa/mroonga,yoku0825/mroonga,yoku0825/mroonga,mroonga/mroonga,naoa/mroonga,mroonga/mroonga,yoku0825/mroonga,naoa/mroonga,mroonga/mroonga,yoku0825/mroonga,naoa/mroonga,naoa/mroonga,naoa/mroonga