BUG: Quick fix for Mellin test

Quick fix for Mellin test.
The issue might not be coming from OTB but rather from ITK or FFTW. This bug might occur in other situation but this is the best we have for now.

Bug description : At the end of the executable ffttw needs to clean its threads. During this process it needs to wait for its worker to finish their job, however during interaction with mutex/semaphore the WaitForSingleObject called on the first worker, is waiting an infinitely whereas we are already out of the computation step (images are already on the disk and compared). Thus the error...

added bug patch labels

To add some information, it may be the same bug we had with DomainTransform application during FFT computations.

changed milestone to %6.6.1

mentioned in issue #1722 (closed)

merged

mentioned in commit 827ed710

mentioned in merge request !313 (merged)

changed milestone to %7.0.0