Fix ENABLE_CLAZY option with clazy >= 1.5

Summary:
clazy 1.5 renamed its plugin from from ClangLazy.so to
ClazyPlugin.so and from clang-lazy to clazy.

Reviewers: apol, smartins

Subscribers: kde-frameworks-devel, kde-buildsystem

Tags: Frameworks, Build System

Differential Revision: https://phabricator.kde.org/D18680