Fix crashes/assertions related to fb_intercept and reentry

If a function was called via (re)enterVM, and it didn't yet
have a prolog, and it was unable to get the write lease, and it was
intercepted, and the intercept handler asked for the original function
to be skipped, fcallHelper didn't return correctly, typically resulting
in the original function being re-executed, and then re-intercepted -
except that it was one level deeper in the vm-nesting hierarchy.

Eventually, it crashed.
Make libevent takeover support have better behavior when takeover not done

Currently, when we have takeover configured we don't close() the listen
socket until the hhvm process dies. This is bad because the loadbalancer
will continue to try to connect to the server and we will throw those
requests away.

This diff ensures that we always close the listen socket during server
shutdown.
Possible Leak in UnitEmitter

I was looking at a jemalloc profile of HPHP ram and noticed
250 MB of RAM allocated from UnitEmitter::UnitEmitter. This
doesn't make sense since the memory is released on destruction.
I think that we're calling setBc which leaks the memory
Kill InclOpLocal

This one's an artifact of ReqMod and ReqSrc, which don't exist anymore.
Cache the contents of systemlib.php for use by the debugger, if debugging.

Instead of calling get_systemlib every time the debugger client needs to list source from systemlib.php, use a cached copy of the source string. Only do this if debugging is enabled.
clone config.hdf from slow to large_memory

It failed again with my other config.hdf commit already in the tree. Lets try the whole config I guess...
kill dead attributes

I was in here and noticed a few of them aren't used.
Changed lookupIR in targetcache.cpp to not require a VMRegAnchor

Updated lookupIR functions in StaticMethodCache and StaticMethodFCache
to accept the FP as an argument.
Added AssertThis opcode and modified translator to emit it

AssertThis is now emitted when IR is generated rather than simply
setting the isThisAvailable flag.
Parse nested namespaces in break point specifications.

Changed the parser for break point specifications to allow nested namespace qualifiers. Also extended this to the exception command.
Remove StringOffset and String.lval() overloaded functions.

These are dead code, except for a few tests.
Recover from C++ exceptions

Recover from C++ exceptions so that PSP does not think ASIO is running. Fixes a segfault when ASIO fails on internal invariant violation in runUntil() with m_current == nullptr.
WIterNext and WIterNextK should break BBs

They're control flow instructions.
fix text

oops
Remove NEW(Variant) uses in ext_mysql
Remove SmartAllocator support from Variant @override-unit-failures

It looks like this is all it takes now.  I couldn't find any
of the old .inc file stuff; I guess it went away at some point.
Remove Variant's o_foo member functions @override-unit-failures
Delete various dead "currentRef"-related functions

endRef() is also almost dead, but not quite yet...
Add comments and type information to break_point

Non functional changes to make the code more readable.
Clean up the hphp/system folder

I noticed that directorty structure of hphp/system was a bit scattered, so
I consolidated things to reduce the total number of folders and to put
related things together with each other.

This diff moves the contents of "hphp/system/classes_hhvm" into
"hphp/system", it moves the contents of "hphp/system/lib" into
"hphp/system", moves "hphp/idl" to "hphp/system/idl", and moves the
contents of "hphp/system/globals" into "hphp/system/idl".