Fix licenses
Fix licenses

In https://github.com/lxqt/liblxqt/pull/66:

> some files in cmake/modules are under BSD-3-clause

Looks like those CMake files are removed after liblxqt moved to lxqt-build-tools https://github.com/lxqt/liblxqt/pull/109.
lxde/liblxqt,lxde/liblxqt