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

*** 427,438 ****
          t->t_startpc = proc;
          t->t_procp = pp;
          t->t_clfuncs = &sys_classfuncs.thread;
          t->t_cid = syscid;
          t->t_pri = pri;
!         t->t_stime = ddi_get_lbolt();
!         t->t_schedflag = TS_LOAD | TS_DONT_SWAP;
          t->t_bind_cpu = PBIND_NONE;
          t->t_bindflag = (uchar_t)default_binding_mode;
          t->t_bind_pset = PS_NONE;
          t->t_plockp = &pp->p_lock;
          t->t_copyops = NULL;
--- 427,437 ----
          t->t_startpc = proc;
          t->t_procp = pp;
          t->t_clfuncs = &sys_classfuncs.thread;
          t->t_cid = syscid;
          t->t_pri = pri;
!         t->t_schedflag = 0;
          t->t_bind_cpu = PBIND_NONE;
          t->t_bindflag = (uchar_t)default_binding_mode;
          t->t_bind_pset = PS_NONE;
          t->t_plockp = &pp->p_lock;
          t->t_copyops = NULL;