Update rustfmt to rust-lang/rustfmt@d6829d

diff --git a/src/tools/rustfmt b/src/tools/rustfmt
index be135599ef5e54b5219f9adec68e1ee267ea0584..d6829d62dca64dfe7ceaa96d1a9c1cd36428221d 160000 (submodule)
--- a/src/tools/rustfmt
+++ b/src/tools/rustfmt
@@ -1 +1 @@
-Subproject commit be135599ef5e54b5219f9adec68e1ee267ea0584
+Subproject commit d6829d62dca64dfe7ceaa96d1a9c1cd36428221d