Progress on SPARC

[Mark Kettenis]

Thanks to Ben Collins and the Debian project, I've completed the
64-bit GNU/Linux SPARC support.  In order to debug 64-bit code you'll
need to compile GDB with a compiler that produces 64-bit code.  If you
use a 32-bit compiler and configure for sparc64-unknown-linux-gnu
anyway, you'll probably end up with a debugger that doesn't work.
I'll see if I can fix that later.

There is also some support for 64-bit Solaris SPARC on the branch now,
but I don't know if it'll work.

I still have to revicve NetBSD (both 32-bit and 64-bit) before I can
merge this stuff into mainline.

Mark