Lock escalation causes all lock trees (all dbs in an environment)
to escalate their locks.
This is useful, since we can have one lock tree/db holding 99% of the locks
and then we run out of locks on a different lock tree.

git-svn-id: file:///svn/tokudb@2952 c7de825b-a66e-492c-adef-691d508d4ae1