Better accounting of running processes.

Reference: /n/patches.lsub.org/patch/nrunning
Date: Tue Jul 10 14:41:36 CES 2012
Signed-off-by: paurea@lsub.org

--- /sys/src/nix/port/proc.c	Tue Jul  3 10:40:22 2012
+++ /sys/src/nix/port/proc.c	Tue Jul 10 14:40:39 2012
@@ -114,6 +114,8 @@
 			unlock(&procalloc);
 			break;
 		}
+		if(up->state != Exotic)
+			adec(&run.nrunning);
 		up->mach = nil;
 		updatecpu(up);
 		up = nil;
@@ -131,6 +133,7 @@
 	char dummy;
 
 	if(&dummy < (char*)up->kstack + 4*KiB){
+print("kstack is %p %p\n", up->kstack, &dummy);
 		print("tc kernel stack overflow, cpu%d stopped\n", m->machno);
 		DONE();
 	}
@@ -187,8 +190,6 @@
 
 		stackok();
 
-		if(up->state != Exotic)
-			adec(&run.nrunning);
 		procsave(up);
 		mmuflushtlb(m->pml4->pa);
 		if(setlabel(&up->sched)){