Fix count_all_results when ordering

[addbee]

Fixes error introduced in v3 when there is a pending qr_order_by (used typically in pagination to get a count before results)

Method adapted from v2 DB_active_rec line 911

[narfbg]

You're saying it fixes an error, but you're not saying what error that is ...

[addbee]

Using the sqlsrv driver, query builder generates the following query for count_all_results

SELECT COUNT(*) AS "numrows" FROM "tenants" LEFT JOIN "properties" "p" ON "p"."id" = "tenants"."property_id" WHERE "tenants"."deleted_date" =0 AND "tenants"."company_id" = '72' ORDER BY "tenants"."property_id" ASC

In SQL server, this generates the error

Column "tenants.property_id" is invalid in the ORDER BY clause because it is not contained in either an aggregate function or the GROUP BY clause

In the previous version of CodeIgniter, the order by clause was omitted during compilation of the count_all_results query, to avoid this error.

MySQL seems more forgiving of this issue, but omitting the ORDER BY for count_all_results will not change the output for other database drivers