Remove QtAlgorithms usage from QtScript.

QtAlgorithms is getting deprecated,
see http://www.mail-archive.com/development@qt-project.org/msg01603.html

Change-Id: If4dc8f69fd75315390a4850be732715064f5fdd8
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>