Add fnl build target

services/http_server/http_server_apptest.cc

Index: services/http_server/http_server_apptest.cc
diff --git a/services/http_server/http_server_apptest.cc b/services/http_server/http_server_apptest.cc
index 58f1ff436424d0798d00ad9722b4b38d480fc71e..494b68ad00dd26a274dcb49a3d8caa8a97065a92 100644
--- a/services/http_server/http_server_apptest.cc
+++ b/services/http_server/http_server_apptest.cc
@@ -26,7 +26,7 @@ void WriteMessageToDataPipe(
   MojoCreateDataPipeOptions options = {sizeof(MojoCreateDataPipeOptions),
                                        MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE,
                                        1,
-                                       message.size()};
+                                       static_cast<uint32_t>(message.size())};
 
   MojoResult result =
       CreateDataPipe(&options, &producer_handle_, data_pipe_consumer);