Make the bootsrap respect the contentAddressedByDefault setting

Patch every `derivation` call in the bootsrap process to add it a
conditional `__contentAddressed` parameter.

That way, passing `contentAddressedByDefault` means that the entire
build closure of a system can be content addressed

pkgs/stdenv/generic/default.nix

@@ -84,6 +84,11 @@ let
       allowedRequisites = allowedRequisites
         ++ defaultNativeBuildInputs ++ defaultBuildInputs;
     }
+    // lib.optionalAttrs (config.contentAddressedByDefault or false) {
+      __contentAddressed = true;
+      outputHashAlgo = "sha256";
+      outputHashMode = "recursive";
+    }
     // {
       inherit name;