Update rustfmt to the latest master

topecongiro · topecongiro · commit d8ffe7ddbfa4 · 2019-07-17T13:54:57.000+09:00
diff --git a/src/tools/rustfmt b/src/tools/rustfmt
@@ -1 +1 @@
-Subproject commit 65931cd09d5be3039d907015234c3fd5325c289d
+Subproject commit 66c27c9161b2aa70c2902807be12952bd4a0a62b
