3006 VERIFY[S,U,P] and ASSERT[S,U,P] frequently check if first argument is zero

@@ -342,11 +342,11 @@
         if (0 == zfeature_lookup_guid(feature.fi_guid, NULL))
                 fatal("'%s' is a real feature, will not enable");
         if (0 == zap_contains(mos, spa->spa_feat_desc_obj, feature.fi_guid))
                 fatal("feature already enabled: %s", feature.fi_guid);
 
-        VERIFY3U(0, ==, dsl_sync_task_do(spa->spa_dsl_pool, NULL,
+        VERIFY0(dsl_sync_task_do(spa->spa_dsl_pool, NULL,
             feature_enable_sync, spa, &feature, 5));
 
         spa_close(spa, FTAG);
 
         free(desc);

@@ -440,11 +440,11 @@
         }
 
         if (decr && !spa_feature_is_active(spa, &feature))
                 fatal("feature refcount already 0: %s", feature.fi_guid);
 
-        VERIFY3U(0, ==, dsl_sync_task_do(spa->spa_dsl_pool, NULL,
+        VERIFY0(dsl_sync_task_do(spa->spa_dsl_pool, NULL,
             decr ? feature_decr_sync : feature_incr_sync, spa, &feature, 5));
 
         spa_close(spa, FTAG);
 }