From: Peter Chubb <peterc@gelato.unsw.edu.au>

Currently, do_setitimer() is used in several files, but doesn't appear
in any header.  Thus its declaration is repeated in some files, and
its use causes a warning in others (because there is no declaration
present).

This patch:
     -- adds a couple of declarations to linux/times.h
     -- removes the (now duplicate) declarations from other files.