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The idea of the patch
is that every cursor gets its own lock id for table level locking.
Thus cursors are protected from updates performed within the same 
connection. Additionally a list of transient (must be closed at
commit) cursors is maintained and all transient cursors are closed
when necessary. Lastly, this patch adds support for deadlock
timeouts to TLL locking when using cursors.
+ post-review fixes.


include/thr_lock.h:
  - add a notion of lock owner to table level locking. When using
    cursors, lock owner can not be identified by a thread id any more, 
    as we must protect cursors from updates issued within the same 
    connection (thread). So, each cursor has its own lock identifier to 
    use with table level locking.
  - extend return values of thr_lock and thr_multi_lock with
    THR_LOCK_TIMEOUT and THR_LOCK_DEADLOCK, since these conditions
    are now possible (see comments to thr_lock.c)
mysys/thr_lock.c:
  Better sup...