We didn't watch the symbolic link itself before, only the final link
target. We are watching the symbolic link and the final link target now.
Ugly hack: We need to work around QTBUG-15522. The inotify and kqueue
based file system watcher engines (Linux + Mac) don't report changes to
symbolic links. The workaround is to use the polling engine *only for
the links themselves*. The only way to force the use of the polling
engine is by using the auto test hook in QFileSystemWatcher.