Support disarming timer

src/header/time/mod.rs

@@ -64,6 +64,7 @@ pub(crate) struct timer_internal_t {
     pub process_pid: platform::types::pid_t,
 }
 
+#[cfg(target_os = "redox")]
 impl timer_internal_t {
     pub unsafe fn from_raw(timerid: timer_t) -> &'static Mutex<Self> {
         unsafe { &*(timerid as *const Mutex<Self>) }

src/platform/redox/mod.rs

@@ -1392,6 +1392,11 @@ impl Pal for Sys {
             Self::timer_gettime(timerid, ovalue)?;
         }
 
+        if value.it_value.is_zero() {
+            timer_st.next_wake_version += 1;
+            return Ok(());
+        }
+
         timer_st.next_wake_time = {
             let mut val = value.clone();
             if flags & TIMER_ABSTIME == 0 {