libobs: Update compare-exchange pattern

Use function that updates previous value automatically.

Also load initial value seq_cst to be safe.

libobs/obs-internal.h

@@ -543,12 +543,12 @@ static inline bool obs_weak_ref_release(struct obs_weak_ref *ref)
 
 static inline bool obs_weak_ref_get_ref(struct obs_weak_ref *ref)
 {
-	long owners = ref->refs;
+	long owners = os_atomic_load_long(&ref->refs);
 	while (owners > -1) {
-		if (os_atomic_compare_swap_long(&ref->refs, owners, owners + 1))
+		if (os_atomic_compare_exchange_long(&ref->refs, &owners,
+						    owners + 1)) {
 			return true;
-
-		owners = ref->refs;
+		}
 	}
 
 	return false;

libobs/obs-scene.c

@@ -1532,12 +1532,12 @@ void obs_scene_enum_items(obs_scene_t *scene,
 
 static obs_sceneitem_t *sceneitem_get_ref(obs_sceneitem_t *si)
 {
-	long owners = si->ref;
+	long owners = os_atomic_load_long(&si->ref);
 	while (owners > 0) {
-		if (os_atomic_compare_swap_long(&si->ref, owners, owners + 1))
+		if (os_atomic_compare_exchange_long(&si->ref, &owners,
+						    owners + 1)) {
 			return si;
-
-		owners = si->ref;
+		}
 	}
 	return NULL;
 }