Do not add return type to constructors declaration when editing definition in signature assistant.
BUG: 365420
Reviewers: kfunk, mwolff, KDevelop, brauch
Reviewed By: mwolff, KDevelop, brauch
Subscribers: brauch, apol, KDevelop, kdevelop-devel
Tags: KDevelop
Differential Revision: https://phabricator.kde.org/D11291