title: Error installing mysql2: Failed to build gem native extension
body: <p>I am having some problems when trying to install <code>mysql2</code> gem for Rails. When I try to install it by running <code>bundle install</code> or <code>gem install mysql2</code> it gives me the following error:</p>
  
  <blockquote>
    <p>Error installing mysql2: ERROR: Failed to build gem native extension.</p>
  </blockquote>
  
  <p>How can I fix this and successfully install <code>mysql2</code>?</p>