title: Downgrade libc6 version
body: <p><code>ldd --version</code> shows that I have Ubuntu GLIBC 2.27-3ubuntu1, and I need a version &lt;= 2.24.
  Tried to use <code>sudo apt-get install libc6==2.23-0ubuntu1</code> but it says this version cannot be found. I have searched on <a href="https://packages.ubuntu.com/search?suite=cosmic&amp;section=all&amp;arch=any&amp;keywords=libc6&amp;searchon=names" rel="nofollow noreferrer">Ubuntu packages</a> to find a version that suits my requirements but couldn't find anything.</p>
  
  <p>Can anyone help to downgrade my libc6? I need my gcc to compile with GLIBC &lt;= 2.24 for a plugin I'm making. </p>