FFI 64-bit updates - progress report

 
I now have FFI working on a 64-bit AMD Linux system for both 32-bit and 64-bit
images. All unit tests pass, including some new tests that I added to provide
more coverage of the FFI primitives. The X11Display examples also work.

This is using the "cdecl" interface in platforms/unix/plugins/SqueakFFIPrims/lib-anyffi.c.
The next step will be to move the changes to a 32 bit Linux system and do the updates
to platforms/unix/plugins/SqueakFFIPrims/x86-sysv.c.

This is work in progress, but I'm attaching a snapshot of the work that I have
done so far. There are changes to the VM, the FFI plugin, and to the FFI support
classes in the image (note: after applying the changes, classes with cdecl pragmas
must be recompiled).

More to follow,

Dave