Update www/apache-tomcat8 to 8.0.47.

Notable changes:

- A fix for CVE-2017-12617.
- Add ExtractingRoot, a new WebResourceRoot implementation that extracts
  JARs to the work directory for improved performance when deploying
  packed WAR files.
- Update the packaged version of the Tomcat Native Library to 1.2.14

Full changelog:

  https://tomcat.apache.org/tomcat-8.0-doc/changelog.html

(fhajny)