Further improve mmap() locking story

The way to use double linked lists, is to remove all the things you want
to work on, insert them into a new list on the stack. Then once you have
all the work items, you release the lock, do your work, and then lock it
again, to add the shelled out items back to a global freelist.

libc/intrin/maps.h

@@ -39,7 +39,6 @@ struct AddrSize {
 
 extern struct Maps __maps;
 
-void *randaddr(void);
 void __maps_init(void);
 void __maps_lock(void);
 void __maps_check(void);