Make target_link_libraries for kdeinit_dolphin PRIVATE
Summary:
There is no need to add all of kdeinit_dolphin's
dependencies (including the static archive) when
linking dolphin; kdemain is the only needed symbol.
Mark the link libraries PRIVATE to simplify the
link command for dolphin.
Reviewers: Dolphin, elvisangelaccio
Reviewed By: elvisangelaccio
Subscribers: asturmlechner, kfm-devel
Tags: Dolphin
Differential Revision: https://phabricator.kde.org/D12931