[BUGFIX] Regression: filelistFolderTree constructor is recursive

After fix of compatibility constructor, the real constructor
(__construct) is missing. This leads to a recursive call on
itself and thus crashes.

Change-Id: Ic788b8dfb9ae42a4ad7c1b9a122f31de1df98741
Fixes: #28354
Releases: 4.6
Reviewed-on: http://review.typo3.org/3445
Reviewed-by: Georg Ringer
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers