update Miri

RalfJung · RalfJung · commit 4eb64c842b73 · 2020-11-30T18:15:19.000+01:00
diff --git a/Cargo.lock b/Cargo.lock
@@ -2131,6 +2131,7 @@ dependencies = [
  "rustc-workspace-hack",
  "rustc_version",
  "shell-escape",
+ "smallvec 1.4.2",
 ]
 
 [[package]]
diff --git a/src/tools/miri b/src/tools/miri
@@ -1 +1 @@
-Subproject commit 746ea5b141baf1f86c2ad17753a37b135e0c1aa3
+Subproject commit 47acece7aa25d7b5edfae0bfd4b94e6e55a7b4b0
