update miri (Windows tests fixed)

RalfJung · RalfJung · commit 114dc6916606 · 2018-07-17T11:40:57.000+02:00
diff --git a/src/tools/miri b/src/tools/miri
@@ -1 +1 @@
-Subproject commit ff64b420ecc1762dee6c9b9b211850be68cd9765
+Subproject commit f18fc27b6f1b07e1bc6f61764cd74f59d29956b8
