License maintenance: GPLv2 -> GPLv2+
Summary:
For most authors this uses the standing pre-approval from
https://techbase.kde.org/Projects/KDE_Relicensing, explicit
approval is needed from KDAB (hereby granted) and Andras Mantia.
This is the second batch for mailcommon, there's now still a handful
of cases left that need more research.
Reviewers: amantia
Subscribers: kde-pim
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D16969