pingserver: add --quiet option

Change-Id: I7e61383e587044fd65a50e4dee58a020d3b292ad
Refs: #4673
diff --git a/tools/ping/server/tracer.cpp b/tools/ping/server/tracer.cpp
index 5f5150a..51b191c 100644
--- a/tools/ping/server/tracer.cpp
+++ b/tools/ping/server/tracer.cpp
@@ -28,7 +28,9 @@
 Tracer::Tracer(PingServer& pingServer, const Options& options)
   : m_options(options)
 {
-  pingServer.afterReceive.connect([this] (const Name& name) { onReceive(name); });
+  if (!m_options.wantQuiet) {
+    pingServer.afterReceive.connect([this] (const Name& name) { onReceive(name); });
+  }
 }
 
 void