HEADS UP: aarch64 port in progress

I've been adding aarch64 (ARMv8 64-bit) support to NetBSD in a private tree.

It uses binutils as does every other port but the only compiler being 
used is clang.  This is due to waiting to make a clang only port and 
the lack of aarch64 support in the in-tree gcc (which will solved when 
we upgrade to gcc 4.8).

So far, I have the userland done so that 

	build.sh -m evbarm64-el distribution sets 

will successfully produce sets.  Some things are left to do but this
untested should be pretty close to being functional.  I've done my best
to make this effort support big endian as well as little endian but
that's untested.

Now I'll focus on the few remaining things in userland as well as 
starting on the kernel work.

I do not plan on committing this to the tree as the present or in the
near future.  As a person who's lively hood come from consulting, I'm
going to wait until I can get proper compensation for the time expended
on this work.  I'm doing this anticipating that there will be a need 
for this sometime in the coming year as ARMv8 silicon becomes available.

The unified diffs for the current effort are about 1MB in size.