THRIFT-5766 Replace std::endl with "\n"
Patch: Carel Combrink

This closes #2943
diff --git a/contrib/fb303/cpp/ServiceTracker.cpp b/contrib/fb303/cpp/ServiceTracker.cpp
index a2e670c..43e8847 100644
--- a/contrib/fb303/cpp/ServiceTracker.cpp
+++ b/contrib/fb303/cpp/ServiceTracker.cpp
@@ -344,7 +344,7 @@
       break;
     }
     cout << '[' << level_string << "] [" << now_pretty << "] "
-         << message << endl;
+         << message << '\n';
   }
 }