Fix #2517,Add pid support for persistent connection in Redis

Summary: pfsockopen does not supports id. So I changed it stream_socket_client, to handles ids as well.
Closes https://github.com/facebook/hhvm/pull/4291

Reviewed By: @fredemmott

Differential Revision: D1693997

Signature: t1:1693997:1417632135:c2b2b2648ee77d911d00e1da801c8698e591c784
Use LLVM's experimental location records.

Summary: Replace the usage of LLVM's stackmaps with locrecs as locrecs require
less help from HHVM disassembler and do not prevent any
of LLVM optimizations.

Reviewed By: @swtaarrs

Differential Revision: D1711966
Ordering in get_defined_var()

Summary: We want the order to be independent of the internal hash function.
Now try ksort().

Reviewed By: @markw65

Differential Revision: D1710163

Signature: t1:1710163:1417632293:f1612631a5653c479d4dbfa5a6f66b3a25c635a4