MDEV-11311 Create federated table does not work as expected.

FederatedX wasn't discovering prefix keys correctly.
Of course, as it had the HA_NO_PREFIX_CHAR_KEYS table_flag set...

mysql-test/suite/federated/assisted_discovery.result

@@ -31,6 +31,38 @@ id	group	a\\b	a\\	name
 1	1	2	NULL	foo
 2	1	2	NULL	fee
 DROP TABLE t1;
+create table t1 (
+a bigint(20) not null auto_increment,
+b bigint(20) not null,
+c tinyint(4) not null,
+d varchar(4096) not null,
+primary key (a),
+key (b,c,d(255))
+);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` bigint(20) NOT NULL AUTO_INCREMENT,
+  `b` bigint(20) NOT NULL,
+  `c` tinyint(4) NOT NULL,
+  `d` varchar(4096) NOT NULL,
+  PRIMARY KEY (`a`),
+  KEY `b` (`b`,`c`,`d`(255))
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+create table t1 engine=federated
+connection='mysql://root@127.0.0.1:SLAVE_PORT/test/t1';
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` bigint(20) NOT NULL AUTO_INCREMENT,
+  `b` bigint(20) NOT NULL,
+  `c` tinyint(4) NOT NULL,
+  `d` varchar(4096) NOT NULL,
+  PRIMARY KEY (`a`),
+  KEY `b` (`b`,`c`,`d`(255))
+) ENGINE=FEDERATED DEFAULT CHARSET=latin1 CONNECTION='mysql://root@127.0.0.1:SLAVE_PORT/test/t1'
+drop table t1;
+drop table t1;
 DROP TABLE IF EXISTS federated.t1;
 DROP DATABASE IF EXISTS federated;
 DROP TABLE IF EXISTS federated.t1;

mysql-test/suite/federated/assisted_discovery.test

@@ -30,5 +30,29 @@ connection slave;
 SELECT * FROM t1;
 DROP TABLE t1;
 
+#
+#
+#
+create table t1 (
+  a bigint(20) not null auto_increment,
+  b bigint(20) not null,
+  c tinyint(4) not null,
+  d varchar(4096) not null,
+  primary key (a),
+  key (b,c,d(255))
+);
+show create table t1;
+
+connection master;
+--replace_result $SLAVE_MYPORT SLAVE_PORT
+eval create table t1 engine=federated
+  connection='mysql://root@127.0.0.1:$SLAVE_MYPORT/test/t1';
+--replace_result $SLAVE_MYPORT SLAVE_PORT
+show create table t1;
+drop table t1;
+
+connection slave;
+drop table t1;
+
 source include/federated_cleanup.inc;
 

storage/federatedx/ha_federatedx.h

@@ -330,7 +330,7 @@ class ha_federatedx: public handler
     return (HA_PRIMARY_KEY_IN_READ_INDEX | HA_FILE_BASED
             | HA_REC_NOT_IN_SEQ | HA_AUTO_PART_KEY | HA_CAN_INDEX_BLOBS |
             HA_BINLOG_ROW_CAPABLE | HA_BINLOG_STMT_CAPABLE | HA_CAN_REPAIR |
-            HA_NO_PREFIX_CHAR_KEYS | HA_PRIMARY_KEY_REQUIRED_FOR_DELETE |
+            HA_PRIMARY_KEY_REQUIRED_FOR_DELETE |
             HA_PARTIAL_COLUMN_READ | HA_NULL_IN_KEY);
   }
   /*