There is no naked-lisp.core file anymore as it is not needed. (pcl
can recompile itself now)

The reference dir is the /usr/include parts that I used in making the
unix-glibc2.lisp file, so that I can adapt quickly to changes in the
header files.

There is now direct syscall support, with a few VOP's in 
src/compiler/x86/syscall-linux.lisp that get used in
src/code/unix-syscall.lisp and src/code/syscall-internet.lisp. This
is needed for mp and to gain stability by not using the ever-changing
glibc...
