clean up scheduler before gsoc. nil not 0 for ptrs.

Reference: /n/atom/patch/applied/procnil
Date: Thu May 15 04:51:43 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/port/proc.c	Thu May 15 04:51:43 2014
+++ /sys/src/nix/port/proc.c	Thu May 15 04:51:43 2014
@@ -450,13 +450,13 @@
 	}
 
 	/*
-	 *  p->mach==0 only when process state is saved
+	 *  p->mach == nil only when process state is saved
 	 */
-	if(p == 0 || p->mach){
+	if(p == nil || p->mach != nil){
 		unlock(sch);
 		return nil;
 	}
-	if(p->rnext == 0)
+	if(p->rnext == nil)
 		rq->tail = l;
 	if(l)
 		l->rnext = p->rnext;
@@ -715,7 +715,7 @@
 	sch = procsched(p);
 	lock(sch);
 	/* Only reliable way to see if we are Running */
-	if(p->mach == 0) {
+	if(p->mach == nil) {
 		p->newtlb = 1;
 		ok = 1;
 	}
@@ -776,7 +776,7 @@
 	p->noteid = incref(&noteidalloc);
 	if(p->pid <= 0 || p->noteid <= 0)
 		panic("pidalloc");
-	if(p->kstack == 0)
+	if(p->kstack == nil)
 		p->kstack = smalloc(KSTACK);
 
 	/* sched params */
@@ -1038,7 +1038,7 @@
 	if(dolock)
 		qlock(&p->debug);
 
-	if(flag != NUser && (p->notify == 0 || p->notified))
+	if(flag != NUser && (p->notify == nil || p->notified))
 		p->nnote = 0;
 
 	ret = 0;
@@ -1220,8 +1220,8 @@
 	 */
 	if(up->kp == 0) {
 		p = up->parent;
-		if(p == 0) {
-			if(exitstr == 0)
+		if(p == nil) {
+			if(exitstr == nil)
 				exitstr = "unknown";
 			panic("boot process died: %s", exitstr);
 		}
@@ -1334,7 +1334,7 @@
 	}
 
 	lock(&up->exl);
-	if(up->nchild == 0 && up->waitq == 0) {
+	if(up->nchild == 0 && up->waitq == nil) {
 		unlock(&up->exl);
 		error(Enochild);
 	}
@@ -1365,7 +1365,7 @@
 	uintptr bss;
 	char *s;
 
-	if(p == 0)
+	if(p == nil)
 		return;
 
 	bss = 0;
@@ -1375,7 +1375,7 @@
 		bss = p->seg[BSEG]->top;
 
 	s = p->psstate;
-	if(s == 0)
+	if(s == nil)
 		s = statename[p->state];
 	print("%3d:%10s pc %#p dbgpc %#p  %8s (%s) ut %ld st %ld bss %#p qpc %#p nl %d nd %ud lpc %#p pri %ud\n",
 		p->pid, p->text, p->pc, dbgpc(p), s, statename[p->state],
@@ -1457,7 +1457,7 @@
 
 	for(sch = run; sch < &run[Nsched]; sch++){
 		for(rq = &sch->runq[Nrq-1]; rq >= sch->runq; rq--){
-			if(rq->head == 0)
+			if(rq->head == nil)
 				continue;
 			print("sch%ld rq%ld:", sch - run, rq-sch->runq);
 			for(p = rq->head; p; p = p->rnext)
@@ -1507,7 +1507,7 @@
 
 	kstrdup(&p->user, eve);
 	kstrdup(&p->text, name);
-	if(kpgrp == 0)
+	if(kpgrp == nil)
 		kpgrp = newpgrp();
 	p->pgrp = kpgrp;
 	incref(kpgrp);