sql_db: more stats expressions, don't mogrify
sql_db: more stats expressions, don't mogrify

This gives a bit better stats, and also improves on the speed, when
sql debugging is enabled. Psycopg2 does have a "query" attribute with
the result of the mogrify, so no need to call that function explicitly.

xrg/openerp-server,xrg/openerp-server