Include class_ as a special C++ name.

This allows the Avian minimalist class library to be compiled.
Fix a crash in SubArray::end()

It was trying to do a dynamic_cast<> on invalid iterators.
Array: add an internal interface so System.arraycopy can access the raw memory directly.
Flesh out the j2c runtime and give it a Makefile.
Import Avian runtime and update the Makefile for it.
Fixup j2c.cpp
Remove all but the headers from the translated runtime library.

We don't need the implementations because the correct way to do
things is to translate your app along with the standard library simultaneously.
The headers are here only to let us compile libj2c

Add some code to StubWriter to exclude generating native stubs for methods
that we're implementing in libj2c