[Performance] QSqlQuery::boundValues has unneeded O(n^2) complexity, can be O(n)

For each bound value a call is made to QSqlResult::private->indexes.index(QHash.index, which is O(n)), which results in overall complexity of O(n^2).

For ORMs that select records by a list of primary or foreign keys this can end up taking much longer than needed.

Attached patch makes the call O(n).