Moved out a lot of code into functions from external_lock and
start_stmt
Fixed a crashing bug at memory alloc failure
Merged the stmt and all variables into one trans variable
Always register start of statement as according to the
interface of the handlers.
Also register for start of transaction when not statement commit
== not autocommit AND no begin - commit ongoing
Now that we registered in a proper manner we also needed to handle
the commit call when end of statement and transaction is ongoing
Added start_stmt_count to know when we have start of statement
for first table