修改CFSqueue从Vec变成红黑树 (#229)

使用了由tickbh编写的rbtree： https://github.com/tickbh/rbtree-rs/blob/master/src/lib.rs

Co-authored-by: tickbh <tickdream125@hotmail.com>

kernel/src/libs/mod.rs

@@ -4,6 +4,7 @@ pub mod list;
 pub mod lockref;
 pub mod mutex;
 pub mod printk;
+pub mod rbtree;
 #[macro_use]
 pub mod refcount;
 pub mod rwlock;