adjust procwired according to suggestions from charles.

Reference: /n/atom/patch/applied2013/procwiredadj
Date: Sun Dec 29 23:42:15 CET 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/port/proc.c	Sun Dec 29 23:42:09 2013
+++ /sys/src/nix/port/proc.c	Sun Dec 29 23:42:11 2013
@@ -854,8 +854,10 @@
 			up->seg[i]->color = up->color;
 	qunlock(&up->seglock);
 
-	while(m->machno != bm)
+	if(m->machno != bm)
 		sched();
+	if(m->machno != bm)
+		panic("procwired: %d != %d", m->machno, bm);
 }
 
 void