third_party/nix: introduce toolchain bundle

This introduces a nix derivation that builds a musl amd64/aarch64
toolchain sysroot.

Change-Id: Iba082edb8fd1f2ab580020bb1c7339a76487f3c8
Reviewed-on: https://review.monogon.dev/c/monogon/+/4006
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
Tested-by: Jenkins CI
diff --git a/third_party/nix/pkgs/util-linux/default.nix b/third_party/nix/pkgs/util-linux/default.nix
new file mode 100644
index 0000000..1935cd3
--- /dev/null
+++ b/third_party/nix/pkgs/util-linux/default.nix
@@ -0,0 +1,11 @@
+{ pkgs }: with pkgs;
+util-linux.override (old: {
+  pamSupport = false;
+  ncursesSupport = false;
+  capabilitiesSupport = false;
+  systemdSupport = false;
+  translateManpages = false;
+  nlsSupport = false;
+  shadowSupport = false;
+  writeSupport = false;
+})