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/MODULE.bazel b/MODULE.bazel
index 0dcb084..139bfc3 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -93,6 +93,7 @@
 bazel_dep(name = "rules_proto", version = "7.1.0")
 bazel_dep(name = "rules_proto_grpc_doc", version = "5.1.0")
 bazel_dep(name = "rules_proto_grpc_buf", version = "5.1.0")
+bazel_dep(name = "rules_foreign_cc", version = "0.14.0")
 
 # Currently supported version are listed here:
 # https://protobuf.dev/support/version-support/
@@ -124,7 +125,10 @@
 
 register_toolchains("//build/toolchain/rust-efi:prost_efi_toolchain")
 
+register_toolchains("//build/toolchain/toolchain-bundle:all")
+
 include("//build/bazel:rust.MODULE.bazel")
 include("//build/bazel:go.MODULE.bazel")
 include("//build/bazel:oci.MODULE.bazel")
 include("//build/bazel:third_party.MODULE.bazel")
+include("//build/bazel:toolchain.MODULE.bazel")