Make all LGPLv2 licenses LGPLv2+ for compatibility with the V3 code
Bug https://bugs.kde.org/show_bug.cgi?id=408071 notes that we have a mix of lgplv2, lgplv2+, gplv2+ and gplv3+ We cannot combine lgplv2-only with gplv3+, so this patch changes the license of all lgplv2-only code to lgplv+.