Update crossbeam-channel to 0.5.2

Test: cd external/rust/crates && atest --host -c
Change-Id: I1dd8965902969ea654a06d17e78181d99dd7bb7e
diff --git a/examples/fibonacci.rs b/examples/fibonacci.rs
index cf22b7a..e6f5e89 100644
--- a/examples/fibonacci.rs
+++ b/examples/fibonacci.rs
@@ -10,7 +10,7 @@
     while sender.send(x).is_ok() {
         let tmp = x;
         x = y;
-        y = tmp + y;
+        y += tmp;
     }
 }