[Debian-med-packaging] Bug#859201: Activate DCMTK private tags

[Mathieu Malaterre]

Package: dcmtk
Version: 3.6.1~20160216-4

Would be nice to add:

-DDCMTK_ENABLE_PRIVATE_TAGS:BOOL=ON

I see instead:

-DDCMTK_WITH_PRIVATE_TAGS:BOOL=ON

I could not figure out if this is a regression or just a typo that has
always been there, but it may look like upstream changed the flag
without backward compatibility.

cheers