uclibc: avoid "Error in reading or end of file" warnings

Thanks to @bjornfor for the advice in
https://github.com/NixOS/nixpkgs/commit/6057d74d1c9cad1b05d5316aa9273297b67941f6

pkgs/os-specific/linux/uclibc/default.nix

···
     ${if cross != null then stdenv.lib.attrByPath [ "uclibc" "extraConfig" ] "" cross else ""}
     $extraCrossConfig
     EOF
-    make oldconfig </dev/null
+    ( set +o pipefail; yes "" | make oldconfig )
   '';
 
   hardeningDisable = [ "stackprotector" ];