While I was working on the TestCodeRun refactor I found two tests about Tainted code. I looked into it and coulnd't get HHVM to compile with TAINTED=1. Then I checked and none of the extension functions we exposed about tainting were used in WWW. Scratching my head I asked, @srenfro and @jdelong, who thought it was dead. So I killed this zombie.
This change is mostly for FB internal organizational reasons.
Building is not effected beyond the fact that the target now
lands in hphp/hhvm/hhvm rather than src/hhvm/hhvm.