MDEV-31781 ALTER TABLE ENGINE=s3 fails

s3 is read-only. No need to update to a read-only engine with LOCK=NONE.

mysql-test/suite/s3/alter.result

@@ -130,3 +130,7 @@ count(*)	sum(a)	sum(b)
 select count(*), sum(a), sum(b) from t1;
 ERROR 42S02: Table 'database.t1' doesn't exist
 drop table t2;
+# MDEV-31781 ALTER TABLE ENGINE=s3 fails
+create table t (a int) engine=Aria;
+alter table t engine=S3, algorithm=copy, lock=none;
+ERROR 0A000: LOCK=NONE is not supported. Reason: S3. Try LOCK=SHARED

mysql-test/suite/s3/alter.test

@@ -93,6 +93,12 @@ select count(*), sum(a), sum(b) from t2;
 select count(*), sum(a), sum(b) from t1;
 drop table t2;
 
+
+--echo # MDEV-31781 ALTER TABLE ENGINE=s3 fails
+create table t (a int) engine=Aria;
+--error ER_ALTER_OPERATION_NOT_SUPPORTED_REASON
+alter table t engine=S3, algorithm=copy, lock=none;
+
 #
 # clean up
 #

storage/maria/ha_maria.h

@@ -67,7 +67,7 @@ class __attribute__((visibility("default"))) ha_maria :public handler
   ~ha_maria() = default;
   handler *clone(const char *name, MEM_ROOT *mem_root) override final;
   const char *index_type(uint key_number) override final;
-  ulonglong table_flags() const override final
+  ulonglong table_flags() const override
   { return int_table_flags; }
   ulong index_flags(uint inx, uint part, bool all_parts) const override final;
   uint max_supported_keys() const override final

storage/maria/ha_s3.cc

@@ -238,6 +238,7 @@ ha_s3::ha_s3(handlerton *hton, TABLE_SHARE *table_arg)
   /* Remove things that S3 doesn't support */
   int_table_flags&= ~(HA_BINLOG_ROW_CAPABLE | HA_BINLOG_STMT_CAPABLE |
                       HA_CAN_EXPORT);
+  int_table_flags|= HA_NO_ONLINE_ALTER;
   can_enable_indexes= 0;
 }