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/test/vtable/vtable.cpp b/test/vtable/vtable.cpp
index bc67382..399630c 100644
--- a/test/vtable/vtable.cpp
+++ b/test/vtable/vtable.cpp
@@ -1,4 +1,5 @@
 #include <sdbusplus/vtable.hpp>
+
 #include <gtest/gtest.h>
 
 static const sdbusplus::vtable::vtable_t example[] = {