CompizPlugin.cmake changes global CMake build settings

CompizPlugin.cmake has several clauses like this:

if (NOT CMAKE_BUILD_TYPE)
             set (CMAKE_BUILD_TYPE "RelWithDebInfo" CACHE STRING "Build type (Debug/Release/RelWithDebInfo/MinSizeRe)" FORCE)
        endif (NOT CMAKE_BUILD_TYPE)

Since CompizPlugin.cmake is a library intended to be included into other build systems, it should never change global settings. All of these need to be removed.

They cause breakage, among other places, when building Unity with pch.