move version definition into generated header instead of passing it on CLI
Summary:
easier to for IDEs to follow where it comes from and also more in line
with how other defines are set in drkonqi
Test Plan: builds
Reviewers: jriddell, apol
Reviewed By: apol
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D19543