remove whole-process swapping
Long before Unix supported paging, it used process swapping to reclaim
memory.  The code is there and in theory it runs when we get *extremely* low
on memory.  In practice, it never runs since the definition of low-on-memory
is antiquated. (XXX: define what antiquated means)
You can check the number of swapout/swapin events with kstats:
$ kstat -p ::vm:swapin ::vm:swapout

*** 1108,1125 ****
  sysdc_globpri(kthread_t *t)
  {
          return (t->t_epri);
  }
  
- /*ARGSUSED*/
- static pri_t
- sysdc_no_swap(kthread_t *t, int flags)
- {
-         /* SDC threads cannot be swapped. */
-         return (-1);
- }
- 
  /*
   * Get maximum and minimum priorities enjoyed by SDC threads.
   */
  static int
  sysdc_getclpri(pcpri_t *pcprip)
--- 1108,1117 ----
*** 1200,1211 ****
                  sysdc_enosys,   /* parmsset */
                  sysdc_nullsys,  /* stop */
                  sysdc_exit,
                  sysdc_nullsys,  /* active */
                  sysdc_nullsys,  /* inactive */
-                 sysdc_no_swap,  /* swapin */
-                 sysdc_no_swap,  /* swapout */
                  sysdc_nullsys,  /* trapret */
                  sysdc_preempt,
                  sysdc_setrun,
                  sysdc_sleep,
                  sysdc_tick,
--- 1192,1201 ----