title: FFmpeg build error "openssl not found" (for iOS on Mac)
body: <p>I want to build FFmpeg with --enable-openssl but it fails saying "Error: openssl not found", although I linked it within the build script (I'm using this <a href="https://github.com/DeviLeo/DLGPlayer/blob/master/How_to_build_ffmpeg_with_openssl.md" rel="nofollow noreferrer">https://github.com/DeviLeo/DLGPlayer/blob/master/How_to_build_ffmpeg_with_openssl.md</a>). </p>
  
  <p>openssl is not connected to FFmpeg as an <strong>external library</strong> as I can verify when calling</p>
  
  <pre><code>./configure --enable-openssl
  </code></pre>
  
  <p>within the ffmpeg folder in a terminal.</p>
  
  <p>How can I set a folder as an external library?</p>