add low memory counters to ods

Summary: add fields for tracking low memory usage to jemalloc stats page. This will get picked up by ods automatically.

Reviewed By: @jasone

Differential Revision: D1537171
Use smart_calloc in NameValueTable

Summary: Don't leak memory.

Reviewed By: @mclarkelauer

Differential Revision: D1545494
More wordpress unfreezing

Summary: sadpanda

Reviewed By: @JoelMarcey

Differential Revision: D1545919
Fix guard relaxation to work with bytecode control flow

Summary: Due to control flow, a local may have multiple type sources at each program point. So change FrameState to keep the set of type sources for each local, instead of a single one. Also, get rid of None type-source kind.

Reviewed By: @alexmalyshev

Differential Revision: D1535860
Fix flush_evaluation_stack

Summary: A test had been inserted to prevent it flushing the stack and rds
for rpc threads; but the test disabled it entirely.

Added a better check.

Reviewed By: @bertmaher, @edwinsmith

Differential Revision: D1545777
Allow vm-stack flushing in rpc threads

Summary: We disabled the flush in rpc threads, on the grounds that the
execution context lives across requests. However, the execution context
is never *required* to live across requests, and could be reset for a
number of reasons at the start of the next request.

So instead, we reset the request, and then flush. This also solves (at
least in practice) the issue of rpc requests keeping treadmill fromd
working.

Reviewed By: @bertmaher, @dariorussi

Differential Revision: D1546288
Add some support for readline.

Summary: I think it would be nice to move parts of hphpd over to PHP-land, and having readline available would help with that.

Reviewed By: @ptarjan

Differential Revision: D1538831
Attempt to fix t5058784

Summary: Avoid a possible race condition with static properties

Reviewed By: @markw65

Differential Revision: D1547427
Fix cmake jemalloc check

Summary: Escaped backslashes or it will fail with "unexpected CAL_symbol, expecting $end"
See 28108aeb
Closes https://github.com/facebook/hhvm/pull/3716

Reviewed By: @sgolemon

Differential Revision: D1547302
Remove some modifications in tests from import_zend_test.py

Summary: These are all invalid now.
Closes https://github.com/facebook/hhvm/pull/3717

Reviewed By: @sgolemon

Differential Revision: D1547305