sparc64 changes in next egcs snapshot

[Doug Evans]

fyi, the next egcs snapshot will generate sparc64 code that is incompatible
with previous code.  This will only affect 64 bit sparc targets
(i.e. sparc64-elf and sparc64-linux).
Over the next week we'll be finishing up these changes so expect some
instability but lasting not longer than a week or so (hopefully).

For those who can't wait to check it out, note that it is known
that there are currently some implementation inefficiencies (e.g. passing
of fp parameters).  This will of course be cleaned up.