Problem :
---------
There was no clear way to do a meta-data only upgrade of partitioned
innodb tables to make use of 5.7 native partitioning.

Solution :
----------
Introduced ALTER TABLE t UPGRADE PARTITIONING;
This will upgrade from old ha_partition based partitioning to native
partitioning if supported by the engine (such as InnoDB). This fix
both implements UPGRADE PARTITIONING in the server and adds support
for it in mysql_upgrade binary.
Base RB: 8780

Reviewed-by: Dmitry Lenev <dmitry.lenev@oracle.com>

RB: 10063