Remove unmeaningful messages of initproc/user_shell

user/src/bin/initproc.rs

@@ -23,12 +23,14 @@ fn main() -> i32 {
                 yield_();
                 continue;
             }
+            /*
             println!(
                 "[initproc] Released a zombie process, pid={}, exit_code={}",
                 pid,
                 exit_code,
             );
+            */
         }
     }
     0
-}
+}

user/src/bin/user_shell.rs

@@ -196,7 +196,7 @@ pub fn main() -> i32 {
                         for pid in children.into_iter() {
                             let exit_pid = waitpid(pid as usize, &mut exit_code);
                             assert_eq!(pid, exit_pid);
-                            println!("Shell: Process {} exited with code {}", pid, exit_code);    
+                            //println!("Shell: Process {} exited with code {}", pid, exit_code);    
                         }
                     } 
                     line.clear();