added lock acquire system call

src/kernel/synch.rs

@@ -37,11 +37,11 @@ impl Semaphore {
 pub struct Lock {
 
     /// Thread owning the lock
-    owner: Option<Rc<RefCell<Thread>>>,
+    pub owner: Option<Rc<RefCell<Thread>>>,
     /// The queue of threads waiting for execution
-    waiting_queue:List<Rc<RefCell<Thread>>>,
+    pub waiting_queue:List<Rc<RefCell<Thread>>>,
     /// A boolean definig if the lock is free or not
-    free: bool
+    pub free: bool
 
 }