cmake HAVE__DUP examples

NauEngine/NauEditorPublic editor/external/libzipconfig/CMakeLists.txt :96 

check_function_exists(_dup HAVE__DUP)

nih-at/libzip CMakeLists.txt :103 

check_function_exists(_dup HAVE__DUP)

flyinghead/flycast core/deps/libzip/CMakeLists.txt :96 

check_function_exists(_dup HAVE__DUP)