ODBC changes

Hi all,

I've just committed the following change.
However I'm not sure existent apps have no problem
with it. Apps would change the parameters for ODBC
API calls and it may fail. Please check your apps.

You could change the text size limit by changing
the MaxLongVarChar driver option. As for query size
limit, you have nothing to do.

 Get rid of the following size limit.
        1) Query size limit(was 65536) for >=7.0 servers.
        2) Text size limit(was 8190) for 7.1 servers.

Hiroshi Inoue