The process and thread initialization/finalization of the query
classifier plugins is handled using the process and thread
initialization/finalization functions in the module object.
However, the top-level query classifier will also need to perform
process and thread initialization when transaction boundaries are
detected using regular expressions.
The setting up and the initialization of the query classifier has
now been separated. The gateway explicitly sets up the query
classifier (i.e. chooses which one to use and what arguments to
provide), but the actual initialization is performed as part of
the general module initialization.
With 2.0.1 or earlier, if a statement contains a trailing NULL,
the statement will inside qc_sqlite.c incorrectly be assumed not
to be the one to be classified with a crash being indirectly the
result.
