Update nixpkgs to latest master

nh2 · nh2 · commit 3954d5bf2532 · 2019-10-20T04:38:15.000+02:00
diff --git a/nixpkgs b/nixpkgs
@@ -1 +1 @@
-Subproject commit d9cc01374235745ea8581174c4335ae9dda86504
+Subproject commit 2c3b2d19cd3844a7b7e02fc80448321aca622574
