feat: alarm系统调用实现 (#710)

* alarm系统调用实现

kernel/src/syscall/mod.rs

@@ -1055,6 +1055,11 @@ impl Syscall {
                 Err(SystemError::EINVAL)
             }
 
+            SYS_ALARM => {
+                let second = args[0] as u32;
+                Self::alarm(second)
+            }
+
             SYS_SHMGET => {
                 let key = ShmKey::new(args[0]);
                 let size = args[1];

kernel/src/syscall/syscall_num.h

@@ -28,7 +28,7 @@
 #define SYS_DUP2 33
 
 #define SYS_NANOSLEEP 35
-
+#define SYS_ALARM 37
 #define SYS_GETPID 39
 
 #define SYS_SOCKET 41