Allow writes during TokuDB table optimization

Registered by rich prohaska

MySQL grabs the MDL_SHARED_NO_READ_WRITE for optimize table. TokuDB's optimize table allows concurrent reads and writes. This patch allows the storage engine to tell MySQL to downgrade the MDL to MDL_SHARED_WRITE before optimize table really does its work. See https://github.com/Tokutek/ft-engine/wiki/Optimize-Table for details and these github commits to MySQL 5.6 https://github.com/Tokutek/mysql56/commit/1a321b6ae70f76da3dc76c944014baab2b7ce1ae
https://github.com/Tokutek/mysql56/commit/a701cea6de67c713d418a319a6a8486da8e07ff2

Blueprint information

Status:
Not started
Approver:
None
Priority:
Not
Drafter:
None
Direction:
Approved
Assignee:
None
Definition:
Approved
Series goal:
Accepted for 5.6
Implementation:
Unknown
Milestone target:
None

Whiteboard

Laurynas: after 5.6.17, OPTIMIZE should be implemented in terms of online ALTER. Setting to "Not" priority and removing the master blueprint dependency for now.

(?)

Work Items

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