This basically targetted symbols.php, and Globals, but ended up
killing a lot more. I could keep adding more and more, but
this seems like a good point to stop and continue with
another diff.
Allow extensions to hook into hphp_process_init and hphp_process_exit
in the same way they could already hook into thread_init/thread_fini.
Also fixed a bug where we didnt actually call the fini funcs (nobody
is using it though).
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.