Fix assert crash when autocompleting with the same thing defined twice in a file

Summary: We were hitting an assert when the same class/func name was defined twice in the same file.

This was because we were oldifying the same name twice, so the second time, it fail with:
hh_server: hphp/hack/src/heap/hh_shared.c:682: hh_move: Assertion `hashtbl[slot2].addr == ((void *)0)' failed.
@emiraga found a bunch of logs of the same error message. This should fix anything to do with the ide utils stuff. If we still see it in the logs after, it might be a bug in Typing_redecl_service.

Reviewed By: @jwatzman

Differential Revision: D1528258
Add OSS benchmarking suite

Summary: Facebook: moving out from facebook/

Reviewed By: @ptarjan

Differential Revision: D1531518
Fix PDO::bindColumn

Summary: when we call Variant.unset() all refs get lost, use Variant.setNull() instead

Fixes #2914
Closes https://github.com/facebook/hhvm/pull/3638

Reviewed By: @JoelMarcey

Differential Revision: D1530475
Set resumed flag before suspending VarEnv

Summary: Recent cleanup changed the order of operations, causing assertion checks
to fail. Make sure the resumed flag is set before attempting to suspend
VarEnv.

Reviewed By: @​aravind

Differential Revision: D1531325