title: "Fatal error: 'EXTERN.h' file not found" while installing Perl modules
body: <p>While trying to install Perl modules like JSON::XS or YAML::XS, i receive the same error:</p>
  <blockquote>
  <p>XS.xs:1:10: fatal error: 'EXTERN.h' file not found</p>
  </blockquote>
  <p>I use MacBook, xCode is up to date, everything else that could help is up to date too.</p>