title: What is the CMake equivalent to "gcc -fvisibility=hidden" when controlling the exported symbol of a shared library?
body: <p>I developed cross platform software in c++. As I know, Linux .so exported all the symbols by default, well through <code>"gcc -fvisibility=hidden"</code> I can set all the exported symbols as hidden, then set <code>__attribute__(visibility("default"))</code> for the class and function I want to export, so I can control what I want to export.</p>
  
  <p>My question is, using CMake, how can I do the work as "gcc -fvisibility=hidden" control?</p>