set proper expire for xdebug cookie

Summary: Transport::setCookie expects a unix timestamp, not simply a number of
seconds. It will also figure out Max-Age for us automatically.
Closes https://github.com/facebook/hhvm/pull/4151

Reviewed By: @sgolemon

Differential Revision: D1663923

Signature: t1:1663923:1415311101:172e40638cf7b37030a5691c0b06890ad20311e0
Add a isHack() method to ReflectionFunction and ReflectionClass

Summary: These methods return if the function/method/class was defined in a Hack
file, whether that is by starting it with <?hh or by setting
Eval.EnableHipHopSyntax to true.

Closes #2286

Closes https://github.com/facebook/hhvm/pull/4121

Reviewed By: @sgolemon

Differential Revision: D1656119

Signature: t1:1656119:1415311234:ca858120023fae957cef0ff86cb71252e8e2f3fb
Refactor sweepable so it is parseable.

Summary: APCLocalArray and some ObjectDatas also extend Sweepable,
which puts the Sweepable object first in memory, so make
it parseable.

before: [vtable][next][prev][persistentCount][pad:32][subclass...]
after:  [vtable][pad:24][kind][persistentCount][next][prev][subclass...]

Reviewed By: @jdelong

Differential Revision: D1660921

Signature: t1:1660921:1415311481:bc24a947ae79ea9d068596167f926bd7b0cdeda1
Remove unused parameter

Summary: I was auditing the use of check_mode in our server init phase,
and found this similarly-named but unused variable in hh_ide.ml

Reviewed By: @joelbeales

Differential Revision: D1664560

Signature: t1:1664560:1415307088:06cbddc35b0234fe16cba8a64c0b1ad1b5dbf7e7
Change mkdir() / rmdir() / unlink() raise warning behavior.

Summary: According to PHP5, mkdir() / rmdir() / unlink() raises warning only if dealing with plain files.

Fixed vfsstream framework test regressions.
Closes https://github.com/facebook/hhvm/pull/4145

Reviewed By: @sgolemon

Differential Revision: D1664121

Signature: t1:1664121:1415312841:5af0c151d3f1ac15114e33398c555c180c13dde9