Install: special processing for pgsql boolean columns

The upgrade of ADOdb library to version 4.96 with Mantis release
1.1.0 introduced a change in the way type 'L' columns are created
(SMALLINT before, BOOLEAN after).

This requires special handling to fix the database schema, because the
normal schema upgrade steps do not cover it (since from the MantisBT
installer's perspective the column type has not changed).

Fixes #16392
Install: pgsql bool check now handles nullable columns

Issue #16392
WIP: Fix install_date_migrate() for pgsql on ADOdb 5.18

The param count was reset by query execution, causing error in the
function due to mismatched bind parameters when calling db_query_bound()
the second time.

@TODO test, report issue

Fixes #
WIP: pgsql travis errors

caused by executing queries with params in wrong order
need to add mechanism to "push" param # and reset it