yield now returns the number of switches done

include/thread.h

diff --git a/include/thread.h b/include/thread.h
index e1ec96c..7ba96e6 100644
--- a/include/thread.h
+++ b/include/thread.h
@@ -13,7 +13,7 @@
 void		threadexitsall(char *);
 void		threadsetname(char*, ...);
 void		threadsetstate(char*, ...);
-void		threadyield(void);
+int			threadyield(void);
 void		_threadready(_Thread*);
 void		_threadswitch(void);
 void		_threadsetsysproc(void);