title: How to specify target ABI in cmake?
body: <p>I'm not sure if my question is correct. But I've got an legacy project which is compiled by cmake into shared library with <code>System V</code> ABI:</p>
  
  <pre><code>$ readelf -a -W /path/to/my/lib/libname.so | grep 'OS/ABI:'
    OS/ABI:                            UNIX - System V
  </code></pre>
  
  <p>But I need it to be <code>UNIX - GNU</code>. How can I make it?</p>
  
  <p>My OS is CentOS. I've tested a hello-world-library compilations and it's <code>UNIX - GNU</code> on this machine. </p>