Code move src/ -> hphp/

This change is mostly for FB internal organizational reasons.
Building is not effected beyond the fact that the target now
lands in hphp/hhvm/hhvm rather than src/hhvm/hhvm.
Update ext_icu_spoof test
Update third_party/folly
Fix LdClsCns

The loaded value is guaranteed to be a Cell, so no exit label (and
check) is needed.
Fix profiling of continuations

In the interpreter, neither ContEnter nor ContExit checked the
surprise flags, resulting in the time being attributed to the
callers. In the jit, ContEnter checked the surprise flags, but
ContExit did not, resulting in what appeared to be highly
recursive profiles.
Implement FPushClsMethodF in HHIR
Delay pushing return address till RetCtrl

LdRetAddr used to modify rsp, which would break
any rsp relative Reload instructions before returning.
Fix assert for LdRetAddr
Fix RetCtrl for Eval.HHIRGenerateAsserts=1
Implemented Issets in HHIR.

Implemented Issets in HHIR. Added 2 new IR opcodes,
IsTypeMem<T> and IsNTypeMem<T>, that test the type of a given Cell* or
Gen*. We should be able to use them for IssetM as well. Fixed a bug in
simplifyIsType: We were not correctly folding the isType query when
the source was a static string. Removed a few unnecessary instructions
that cleared the top bits of a boolean register; booleans are
represented only in the lower byte of a register so its unnecessary to
clear the top bits.
Fix some warnings at -O1

While tracking down gcc 4.7.1 issues I tried a -O1 build,
and got uninitialized variable warnings. None of them is
real, and at -O3 the compiler can figure out that the variables
are never actually used uninitialized.
Get rid of "Ptr" from the name of internal types

shorter
more consistent with other types (e.g. Obj is a pointer too)
makes some of them more consistent, e.g. FuncClassPtr should
actually be FuncPtrClassPtr in the old scheme
Fix shuffleArgs

shuffleArgs() logic was broken if rScratch was used as part
of the suffle.
Don't allow nulls in regexes passed to preg_replace

Summary: If we allow null characters in a regex, then a user could construct a string that ends with "/e\0" and surreptitiously execute an arbitrary piece of code.  With this patch we fatal if a null is found anywhere before the end of the regex (determined by length()).
Macros for getting machine registers

This kind of business obviously doesn't work on non-x64 platforms, so
let's abstract it out into platform-specific macros. I've also changed
some of the associated variable names, to try to break people of the
habit of only thinking about x64.

There are a few instances of this trick remaining, referencing rbx and
r15. These are a little more of a pain to abstract out because their
roles are defined by our internal ABI rather than an architecture's ABI,
so their ARM equivalents will have to be tied to our ARM register
allocation convention. These will have to wait a bit.
Dont leave 1.txt lying around
The trouble with magic numbers...

... is that once you put them into the codebase, the odds of them
showing up where you dont want them go up dramatically.

With a gcc 4.7.1 -O0 build I hit a consistent crash in production
where debugBacktrace had stepped too far, thinking that the
first non-vm frame was in fact a vm frame. It did so because
it looked at the word above the frame, and saw that it contained
c_Continuation::kMagic.

It turns out that fixupWork's isVMFrame left kMagic in $rdx if the
frame really was a generator ($rdx was dead, but still). We then
return from the tc via a serviceReq that doesnt need $rdx (so doesnt
set it), and then (with a following wind, so that $rdx hasnt been
smashed yet) enterTCHelper stores $rdx in info.args[1].

By another staggering coincidence, info.args[1] is at exactly the
right address to make the call into enterTCHelper /look/ like a
a continuation (based on kMagic). So if we then have a catch
which re-enters the TC there's a good chance kMagic is still there
and the next debugBacktrace (or uncaught exception) will crash.

This diff rewrites everything in terms of the C++ stack; we
now say that its a VM frame if its not on the C++ stack.
Fix a bug when throwing from nested FPI regions

Since we now use the original throw location to figure out
which EHEnt applies when propagating from a fault funclet, we need to
check whether we've already unwound the ActRec before doing it again.
Doing it again could cause issues with nested FPI regions (hitting an
assert in sandboxes).
Fix a bug when you print a DefConst of a NamedEntityPtr
Table-drive type checking for IR opcodes

The way type.cpp was handling return types wasn't quite
sufficient for multiple destinations and unfortunately added a step
that's easy to forget when you add new opcodes with the HasDest flag.
Also, assertions about operand types are too distributed through the
code.  Pull everything into a central table, similar to hhbc.h.  This
still leaves several opcodes without type signatures, since figuring
it out got a bit tedious for now.  It did uncover a few documentation
bugs in ir.specification, though.