Don't make use of HNI property type hints if AllFuncsInterceptable is true

Summary: It's too easy for systemlib code to violate the constraints in this
case.  (There's a case that can do so if you turn hphpc optimizations
off---it's only not doing so right now because hphpc makes some transformations
first that make it so renaming the func in question wouldn't break the type
hint.)

Reviewed By: @bertmaher

Differential Revision: D1443244
Make eval stack pushes in interp.cpp use TInitGen instead of TGen

Summary: The cases where it's pushing an F that it doesn't know if it's boxed.
You can't have an Uninit on the stack in these cases.

Reviewed By: @alexmalyshev

Differential Revision: D1445006
Fix a missing "return" in interp-minstr.cpp for a CGetM with final MW

Summary: This wasn't being tripped because it never happens, but it crashes
hhbbc at compile time.  An unrelated change to the emitter made it possible for
one of the unit tests to do this.

Reviewed By: mwang, alexanderm

Differential Revision: D1445466
Remove some dead code from hhbbc/class-util.h

Summary: This used to be used.

Reviewed By: @alexmalyshev

Differential Revision: D1444887
more complete hhi for LibXMLError

Summary: ... previous hhi was missing the properties
  http://php.net/manual/en/class.libxmlerror.php

Reviewed By: @paulcavallaro

Differential Revision: D1449908