CodeGenerators don't need to be virtual anymore.

Reviewed By: @jasone

Differential Revision: D1627033
Update third-party/ to bump folly version
Eliminate m_curInst

Summary: Why use a global when a local will work? This diff inches its
way towards breaking down the class-with-bytecode-methods organization
of CodeGenerator.

Reviewed By: @swtaarrs

Differential Revision: D1626666
Make sure we have non-zero exit status on hack build err

Reviewed By: @jwatzman

Differential Revision: D1617708
Convert IPC to HNI

Summary: fixes #3922

Reviewed By: @markw65

Differential Revision: D1602962
Make vasm-x64.cpp's lowerCalls a little more generic

Summary: It will soon be handling more than just vcall/vinvoke.

Reviewed By: @edwinsmith

Differential Revision: D1622969
Convert process to HNI

Summary: fixes #3934

Reviewed By: @markw65

Differential Revision: D1604838
Delete db code

Summary: Unused these days.

Reviewed By: @ptarjan

Differential Revision: D1628313
Make HTTP status phrases optional with a fallback for known codes

Summary: RFC 7231 defines status line as follows:
"The first line of a response message is the status-line, consisting
of the protocol version, a space, the status code, another
space, a possibly empty textual phrase describing the status code,
and ending with CRLF."

- This basically means response phrase is optional and may be omitted.
In that case, fall back for default response phrase for known codes or
empty string for others.

- Fix usage of explicit HTTP/* header to set response phrase properly,
if set.

- Also synchronize default phrases to match codes defined in RFC.

Closes #3907. Closes #3945. Partially reverts 93a6dc27c9.
Closes https://github.com/facebook/hhvm/pull/3976

Reviewed By: @paulbiss

Differential Revision: D1618243
Add script to add HH_FIXME

Summary: Simple script to take the output of `hh_client --json` and add
a FIXME for every single one.

Reviewed By: @dlreeves

Differential Revision: D1614381
Remove CodeGenerator::m_slocs & m_dlocs

Summary: They're just copied from m_state.locs, so plumb that through
to the handful of callsites that need it, and plumb inst through
to srcLoc() and dstLoc().

Reviewed By: @jdelong

Differential Revision: D1626986