update .clang-format header inclusion order

Added the header inclusion order to the .clang-format file generated
these changes.

Change-Id: Ia31b21d7ea451cac0309828006bc17c27cbd5bd5
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/example/list-users.cpp b/example/list-users.cpp
index d5e59d6..7b5a1a6 100644
--- a/example/list-users.cpp
+++ b/example/list-users.cpp
@@ -1,6 +1,6 @@
-#include <sdbusplus/bus.hpp>
-#include <iostream>
 #include <cstdint>
+#include <iostream>
+#include <sdbusplus/bus.hpp>
 
 /** An example dbus client application.
  *  Calls org.freedesktop.login1's ListUsers interface to find all active