As a user, this often annoyed me that I couldn't get any debugging info
out of the name and then @ahupp asked for it.
I didn't really know what to name closure ones as the name is done at
emission time. So I went with ##{closure}##. I'm not sure how I feel
about that since it will be uncorrelated with the emitted name.
While I was in there, I deleted a lot of unused code.
I'm totally open to other names and ideas.
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.
ptarjan