libc: introduce "jehanne_" namespace

With this commit all functions declared in libc.h have been renamed
with the "jehanne_" prefix. This is done for several reason:

- it removes conflicts during symbol resolution when linking
  standard C libraries like newlib or musl
- it allows programs depending on a standard C library to directly
  link to a library depending on our non standard libc (eg libsec).

To ease transiction two files are provided:

- sys/include/lib9.h that can be included instead of <libc.h> to use
  the old names (via a simple set of macros)
- sys/src/lib/c/lib9.c that can be compiled with a program where the
  macro provided by lib9.h are too dumb (see for example rc or grep).

In the kernel port/lib.h has been modified accordingly and some of
the functions it directly provides has been renamed too (eg malloc
in qmalloc.c and print in devcons.c).

sys/src/lib/thread/kill.c

@@ -20,18 +20,18 @@ threadxxxgrp(int grp, int dokill)
 	Proc *p;
 	Thread *t;
 
-	lock(&_threadpq.lock);
+	jehanne_lock(&_threadpq.lock);
 	for(p=_threadpq.head; p; p=p->next){
-		lock(&p->lock);
+		jehanne_lock(&p->lock);
 		for(t=p->threads.head; t; t=t->nextt)
 			if(t->grp == grp){
 				if(dokill)
 					t->moribund = 1;
 				tinterrupt(p, t);
 			}
-		unlock(&p->lock);
+		jehanne_unlock(&p->lock);
 	}
-	unlock(&_threadpq.lock);
+	jehanne_unlock(&_threadpq.lock);
 	_threadbreakrendez();
 }
 
@@ -41,22 +41,22 @@ threadxxx(int id, int dokill)
 	Proc *p;
 	Thread *t;
 
-	lock(&_threadpq.lock);
+	jehanne_lock(&_threadpq.lock);
 	for(p=_threadpq.head; p; p=p->next){
-		lock(&p->lock);
+		jehanne_lock(&p->lock);
 		for(t=p->threads.head; t; t=t->nextt)
 			if(t->id == id){
 				if(dokill)
 					t->moribund = 1;
 				tinterrupt(p, t);
-				unlock(&p->lock);
-				unlock(&_threadpq.lock);
+				jehanne_unlock(&p->lock);
+				jehanne_unlock(&_threadpq.lock);
 				_threadbreakrendez();
 				return;
 			}
-		unlock(&p->lock);
+		jehanne_unlock(&p->lock);
 	}
-	unlock(&_threadpq.lock);
+	jehanne_unlock(&_threadpq.lock);
 	_threaddebug(DBGNOTE, "Can't find thread to kill");
 	return;
 }
@@ -90,7 +90,7 @@ tinterrupt(Proc *p, Thread *t)
 {
 	switch(t->state){
 	case Running:
-		postnote(PNPROC, p->pid, "threadint");
+		jehanne_postnote(PNPROC, p->pid, "threadint");
 		break;
 	case Rendezvous:
 		_threadflagrendez(t);