and so the engine calls current_thd to derive transaction information;
instead we now pass THD to those functions, it looks more logical
(it makes the implicit current_thd parameter more visible).
Approved by Brian and Monty.
cursor is interpreted latin1 character and Bug#9819 "Cursors: Mysql Server
Crash while fetching from table with 5 million records."
A fix for a possible memory leak when fetching into an SP cursor
in a long loop.
The patch uses a common implementation of cursors in the binary protocol and
in stored procedures and implements materialized cursors.
For implementation details, see comments in sql_cursor.cc
