[REG 5.6->5.7] Windows: Mouse wheel events are not propagated to ForeignWindow properly

Refactoring change in commit https://codereview.qt-project.org/#/c/145236/ added a "... type != Qt::ForeignWindow" check in qwindowswindow.h file, windowsWindowOf() method, and this check prevents mouse wheel events from being propagated to a foreign parent window. Previous implementation baseWindowOf() did not have this check.

The setup is as follows; Native HWND is wrapped to Qt by use of QWindow::fromWinId and a custom QWindows is added as a child to that window.