Make sure that SWP_NPAGES always has the same value in all source

files, so that SWAP_META_PAGES does not vary either.

swap_pager.c ended up with a value of 16, everybody else 8.  Go with
the 16 for now.

This should only have any effect in the "kill processes because we
are out of swap" scenario, where it will make some sort of estimate
of something more precise.

sys/vm/swap_pager.c

@@ -83,12 +83,6 @@ __FBSDID("$FreeBSD$");
 #include <sys/sx.h>
 #include <sys/vmmeter.h>
 
-#ifndef MAX_PAGEOUT_CLUSTER
-#define MAX_PAGEOUT_CLUSTER 16
-#endif
-
-#define SWB_NPAGES	MAX_PAGEOUT_CLUSTER
-
 #include "opt_swap.h"
 #include <vm/vm.h>
 #include <vm/pmap.h>

sys/vm/swap_pager.h

@@ -70,8 +70,12 @@ struct swdevt {
  * pages per allocation.  We recommend you stick with the default of 8.
  * The 16-page limit is due to the radix code (kern/subr_blist.c).
  */
+#ifndef MAX_PAGEOUT_CLUSTER
+#define MAX_PAGEOUT_CLUSTER 16
+#endif
+
 #if !defined(SWB_NPAGES)
-#define SWB_NPAGES 8
+#define SWB_NPAGES	MAX_PAGEOUT_CLUSTER
 #endif
 
 /*