Cpack in the cmake 3.18-version creates invalid control file
containg empty line. 'dpkg' chokes on this control file.
(cherry picked from commit 392aaa11ac)
The new cmake 3.6 now also inserts correctly
this file into its control-file. But the syntax of the control-file
expects the description lines be indented by a space.
Also empty lines (only spaces) are not allowed.
