Bug in scm_getaffinity

[Eli Zaretskii <eliz@gnu.org>]

While working on the MS-Windows emulation of this function, I bumped
into something that looks like a bug in its subroutine:

  static SCM
  cpu_set_to_bitvector (const cpu_set_t *cs)
  {
    SCM bv;
    size_t cpu;

    bv = scm_c_make_bitvector (sizeof (*cs), SCM_BOOL_F);

    for (cpu = 0; cpu < sizeof (*cs); cpu++)
      {
	if (CPU_ISSET (cpu, cs))
	  /* XXX: This is inefficient but avoids code duplication.  */
	  scm_c_bitvector_set_x (bv, cpu, SCM_BOOL_T);
      }

I think using 'sizeof (*cs)' is incorrect here, we need to use
CPU_SETSIZE instead.  The cpu_set_t data type could be an array of bit
masks, in which case counting only bytes in it is wrong: the result is
too small.