1. add EXCL keyword, for syscalls that are excluded from the configured
   kernel. This is to avoid the UNIMPL overloading which is not
   self-explanatory. Right now one cannot tell if something is really
   unimplemented or just excluded from the kernel.
2. fix all EXCL to list the syscall that it is excluded [this is a bug]
3. Add to all ifdef's for excluded syscalls || !defined(_KERNEL) so that
   the userland kdump does not print '#n (excluded syscallname)(...)'
4. Prefix the lfs_ syscalls with sys_; these are the only syscalls that
   do not start with sys_

Please let me know if you have a problem with the above changes.

christos