Fixing my-env to get NIX_CFLAGS_COMPILE and so on

Yes, I still use my-env. I tested that it works on 16.03.

pkgs/misc/my-env/default.nix

@@ -88,6 +88,7 @@ mkDerivation {
         -e '1i initialPath="${toString initialPath}"' \
         "$setupNew" > "$s"
     cat >> "$out/dev-envs/''${name/env-/}" << EOF
+      defaultNativeBuildInputs="$defaultNativeBuildInputs"
       nativeBuildInputs="$nativeBuildInputs"
       propagatedBuildInputs="$propagatedBuildInputs2"
       # the setup-new script wants to write some data to a temp file.. so just let it do that and tidy up afterwards

pkgs/misc/my-env/loadenv.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!@shell@
 
 OLDPATH="$PATH"
 OLDTZ="$TZ"