4829 sema_init(3C) botches the arguments in an example

@@ -104,11 +104,11 @@
 .sp
 .in +2
 .nf
 sema_t sp;
 int count  =  1;
-sema_init(&sp, count, NULL, NULL);
+sema_init(&sp, count, 0, NULL);
 .fi
 .in -2
 
 .sp
 .LP