title: io_stream.lo Error 1 when installing php extension
body: <p>I'm trying to install mongo php extension on OSX 10.11 but the command:</p>
  
  <blockquote>
    <p>sudo pecl install mongo</p>
  </blockquote>
  
  <p>gives the following error:</p>
  
  <pre><code>...
  In file included from /private/tmp/pear/install/mongo/io_stream.c:34:
  /private/tmp/pear/install/mongo/contrib/php-ssl.h:33:10: fatal error: 'openssl/evp.h' file not found
  #include &lt;openssl/evp.h&gt;
           ^
  1 error generated.
  make: *** [io_stream.lo] Error 1
  ERROR: `make' failed
  </code></pre>