Clean up exit flag handing across TVU

bench-streamer/src/main.rs

@@ -81,12 +81,7 @@ fn main() -> Result<()> {
 
         let (s_reader, r_reader) = channel();
         read_channels.push(r_reader);
-        read_threads.push(receiver(
-            Arc::new(read),
-            exit.clone(),
-            s_reader,
-            "bench-streamer",
-        ));
+        read_threads.push(receiver(Arc::new(read), &exit, s_reader, "bench-streamer"));
     }
 
     let t_producer1 = producer(&addr, exit.clone());