mysql57: follow struct st_mysql_show_var change
mysql57: follow struct st_mysql_show_var change

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