[PARISC] Implement 5 argument clone.

* arch/parisc/kernel/process.c (sys_clone): Use 5 args, and process
  CLONE_PARENT_SETTID, CLONE_CHILD_SETTID, CLONE_CHILD_CLEARTID.
  (copy_thread): First cut at CLONE_SETTLS.

Signed-off-by: Carlos O'Donell <carlos@parisc-linux.org>

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>