update the rustfmt submodule

Jorge Aparicio · Jorge Aparicio · commit d893f34e5e31 · 2017-04-05T00:00:04.000Z
diff --git a/rustfmt b/rustfmt
@@ -1 +1 @@
-Subproject commit f63815ee951ce9bb5a5959883b370cf757f7f50a
+Subproject commit d476bef7ed3e75ed79c87717ed351727d7c5d593
