Filetemplate generation: avoid trailing empty line in license header

Summary:
The linebreak behind the last line in a license template results
in another, empty line being added to the generated license header.
Which is assumed to be never intended, but only a result of
additional line formatting in the license template.

Reviewers: KDevelop, kfunk

Reviewed By: KDevelop, kfunk

Subscribers: kfunk, kdevelop-devel

Differential Revision: https://phabricator.kde.org/D7057