Fix crash in qqmlecmascript::sequenceSort with MSVC in debug builds

Fix crash in qqmlecmascript::sequenceSort with MSVC in debug builds

ArrayPrototype.sort allows specifying a compare function implemented in JS,
which we "wrap" and then pass on to std::sort. std::sort with MSVC has
an assertion verifying that the less-than compare function provided is
perfectly consistent in its return values. We don't want JS to easily crash
the entire application and therefore resort to qSort().

Change-Id: Id2c758a7d2bee60f31a7a3971172bca9b3c69af6
Reviewed-by: Lars Knoll <lars.knoll@digia.com>