Add extra information when PostGIS input plugin uses SRID -1

[artemp]

The PostGIS input driver emits a warning that SRID -1 is being used on some input table but does not include any other information.

Changing the warning code in postgis.cpp line 217 to be

        if (srid_ == 0)
        {
            srid_ = -1;
            std::clog << "Postgis Plugin: SRID warning, using srid=-1 for" << table_ << std::endl;
        }

also includes the query specified as input, simplifying problem tracing.