Removed redundant spl0()'s from kernel processes. They were work-arounds

for a bug in fork().

sys/kern/vfs_bio.c

@@ -1697,7 +1697,6 @@ int vfs_update_interval = 30;
 static void
 vfs_update()
 {
-	(void) spl0();		/* XXX redundant?  wrong place? */
 	while (1) {
 		tsleep(&vfs_update_wakeup, PUSER, "update",
 		    hz * vfs_update_interval);

sys/vm/vm_glue.c

@@ -322,7 +322,6 @@ scheduler(dummy)
 	struct proc *pp;
 	int ppri;
 
-	spl0();
 loop:
 	while ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min) {
 		VM_WAIT;

sys/vm/vm_pageout.c

@@ -956,8 +956,6 @@ int add;
 static void
 vm_pageout()
 {
-	(void) spl0();
-
 	/*
 	 * Initialize some paging parameters.
 	 */
@@ -1045,8 +1043,6 @@ vm_daemon()
 	vm_object_t object;
 	struct proc *p;
 
-	(void) spl0();
-
 	while (TRUE) {
 		tsleep(&vm_daemon_needed, PUSER, "psleep", 0);
 		if (vm_pageout_req_swapout) {