it: test explicit sync

src/video/drm/sync_obj.rs

@@ -52,6 +52,11 @@ impl SyncObj {
             importers: Default::default(),
         }
     }
+
+    #[cfg_attr(not(feature = "it"), allow(dead_code))]
+    pub fn fd(&self) -> &Rc<OwnedFd> {
+        &self.fd
+    }
 }
 
 impl Drop for SyncObj {

src/video/drm/wait_for_sync_obj.rs

@@ -27,6 +27,7 @@ pub trait SyncObjWaiter {
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
 struct JobId(u64);
 
+#[must_use]
 pub struct WaitForSyncObjHandle {
     inner: Rc<Inner>,
     id: JobId,