Fix DjVu links pointing to pages with different dimensions

Summary:
Currently the coordinates of a link rectangle in a DjVu document are computed with respect to the size of the page the link is pointing to. Because of that, links only appear in correct places if the dimensions of a target page are the same as of the page containing the link.

The attached file demonstrating the issue contains two pages, one in portrait orientation and one in landscape, the first pointing to the second. The active zone for the link is different from where it is in other viewers.
{F6443987}

Reviewers: #okular

Subscribers: okular-devel

Tags: #okular

Differential Revision: https://phabricator.kde.org/D17194