Give the event handler update thread a name

PiperOrigin-RevId: 214919839
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java b/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java
index 3bb8a48..a8124ac 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java
@@ -954,7 +954,8 @@
                 } catch (InterruptedException e) {
                   // Ignore
                 }
-              });
+              },
+              "cli-update-thread");
       if (updateThread.compareAndSet(null, threadToStart)) {
         threadToStart.start();
       }