Add a comment wondering why our static cpio is configured with creation and passthrough capabilities.

I may test to see if stdenv can be built without these features (I see no reason why not)

svn path=/nixpkgs/trunk/; revision=26698

pkgs/stdenv/linux/make-bootstrap-tools.nix

@@ -77,6 +77,7 @@ rec {
       CLEAR
       CONFIG_STATIC y
       CONFIG_CPIO y
+      # (shlevy) Are these necessary?
       CONFIG_FEATURE_CPIO_O y
       CONFIG_FEATURE_CPIO_P y
     '';