Don't let any instructions sneak in between call/syncpoint/unwind

Summary: The call, exception-edge, and syncpoint are logically all in the
same program point. Until they're smushed together into one vasm
instruction, assert nothing gets between them.

Reviewed By: @alexmalyshev

Differential Revision: D1547922
Remove unnecessary copying in various Dbl ops

Summary: Now that they get virtual registers, we can rip out a bunch
of shuffling code that was making sure values were in good
registers before and after doing an operation.

Reviewed By: @oyamauchi

Differential Revision: D1549800
Force the linker to keep symbols in lowmem on MacOSX

Summary: We can't reach them from the TC with offsets
if they're way up there in 0x0000000100000000 and higher...

Closes #3642

Reviewed By: @ptarjan

Differential Revision: D1552243
Force the php5/ng opcache to on

Summary: Docs say it's on by default, this doesn't appear to be true.

Reviewed By: @JoelMarcey

Differential Revision: D1552557
use hostname instaed of localhost for benchmark requests

Summary: Changes what wordpress does for 301s in an unrealistic way

Reviewed By: @JoelMarcey

Differential Revision: D1552555
Move vasm traces to its own trace mod

Summary: There might be something smarter to do but for now this should be
slightly improved.

Reviewed By: @edwinsmith

Differential Revision: D1552900
Migrate MySQL configs to ::Bind

Summary: Doing this proactively now for a few sites in order for my bad ini node diff to work without a lot of test runner `.expect` changes.

Plus this is the right thing to do anyway.

Note: I removed the `IniSetting::Bind` line because that is now duplicative to the new `Config::Bind` line above it.

Reviewed By: @ptarjan

Differential Revision: D1547854
Remove ini refactoring parameter artificat

Summary: Before `FillInConstants` I had overloaded `Set` to the chagrin of some. I forgot to actually remove `constants_only` as a paramater to `Set`.

Reviewed By: @paulbiss

Differential Revision: D1548688
Better fix for the static property race

Summary: If two threads tried to initialize static properties
for a derived class at the same time, and both tried to initialize
same same persistent property, the second one could overwrite
the property's value with garbage.

Reviewed By: @edwinsmith

Differential Revision: D1552834
Remove Accept-Encoding header

Summary: See comments in nginx.conf.in

Reviewed By: @oyamauchi

Differential Revision: D1552856
import readline tests

Summary: We start to support readline, yey!
Relevant commit 30cb287
Closes https://github.com/facebook/hhvm/pull/3723

Reviewed By: @sgolemon

Differential Revision: D1548083
Fixes to .hhi files for ConstSet, Set, and ImmSet

Summary: D1551381 updated the .hhi files for ConstSet, Set, and ImmSet, but there
were some type mismatch issues. This diff fixes those issues.

Reviewed By: @elgenie

Differential Revision: D1551943