title: PHP intl extension in Docker container
body: <p>I'm trying to load the intl PHP extension in my Docker container, but it doesn't seem to work.</p>
  
  <p>Have already tried this <a href="https://github.com/docker-library/php/issues/57" rel="noreferrer">https://github.com/docker-library/php/issues/57</a> but I still get the same error message:</p>
  
  <pre><code>configure: error: in `/usr/src/php/ext/intl':
  configure: error: C++ preprocessor "/lib/cpp" fails sanity check
  See `config.log' for more details
  </code></pre>
  
  <p>My Docker file looks like this:</p>
  
  <pre><code>RUN apt-get -y update \
  &amp;&amp; apt-get install -y libicu-dev\
  &amp;&amp; docker-php-ext-configure intl \
  &amp;&amp; docker-php-ext-install intl
  </code></pre>
  
  <p>and it's loading from php:fpm</p>
  
  <p>Have anyone gone through this and got to solve the problem? It's getting me nuts.</p>