cmake polyclipping examples

google/filament third_party/libassimp/code/CMakeLists.txt :883 

find_package(polyclipping CONFIG REQUIRED)

vseasky/VersaAssistant assimp/code/CMakeLists.txt :924 

find_package(polyclipping CONFIG REQUIRED)

MBU-Team/OpenMBU engine/lib/assimp/code/CMakeLists.txt :922 

find_package(polyclipping CONFIG REQUIRED)

meemknight/ourCraft thirdparty/assimp-5.2.4/code/CMakeLists.txt :923 

find_package(polyclipping CONFIG REQUIRED)