add .clang-format

Add clang-format file to enable auto-formatting during development and
checking during CI.

Change-Id: I8389797fb47c019b8523057cb99486636efec623
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/local_users.hpp b/local_users.hpp
index e447a25..ac9294f 100644
--- a/local_users.hpp
+++ b/local_users.hpp
@@ -17,5 +17,5 @@
  */
 ipmi_ret_t enableUsers();
 
-}
-}
+} // namespace users
+} // namespace local