zero now the default on ppc

[Gary Benson]

Hi all,

My last commit made the zero-assembler port the default for ppc
and ppc64, and removed support for the ppc-specific port from
the build system.  I also changed the way the core build stuff
worked, since it was really mangled together with the ppc port
and also with a bunch of stuff I did to get the JIT work started.
All this is now cleared up.

There are two things about this that packagers will need to know:

 1) You need libffi installed (in /usr/include and /usr/lib or lib64).

 2) Three paths changed, from:
      j2sdk-image/jre/lib/ppc/client/libjsig.so
      j2sdk-image/jre/lib/ppc/client/libjvm.so
      j2sdk-image/jre/lib/ppc/client/Xusage.txt
    to:
      j2sdk-image/jre/lib/ppc/core/libjsig.so
      j2sdk-image/jre/lib/ppc/core/libjvm.so
      j2sdk-image/jre/lib/ppc/core/Xusage.txt

Sorry about the negative notice, I didn't mean to push the commit
and only realised an hour later :)

Cheers,
Gary