Add bzl_library targets

These are useful for stardoc from other rules repos

proto/BUILD

@@ -1 +1,21 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 # Intentionally left empty (for now).
+
+bzl_library(
+    name = "defs",
+    srcs = ["defs.bzl"],
+    visibility = ["//visibility:public"],
+    deps = ["@rules_proto//proto/private:native"],
+)
+
+bzl_library(
+    name = "repositories",
+    srcs = ["repositories.bzl"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "@bazel_tools//tools/build_defs/repo:http",
+        "@bazel_tools//tools/build_defs/repo:utils",
+        "@rules_proto//proto/private:dependencies",
+    ],
+)

proto/private/BUILD

@@ -1 +1,13 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 # Intentionally left empty (for now).
+
+bzl_library(
+    name = "dependencies",
+    srcs = ["dependencies.bzl"],
+)
+
+bzl_library(
+    name = "native",
+    srcs = ["native.bzl"],
+)

tests/load_from_macro/BUILD

@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 # Copyright 2019 The Bazel Authors. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -20,3 +22,9 @@ proto_library(
     srcs = ["foo.proto"],
     tags = TAGS,
 )
+
+bzl_library(
+    name = "tags",
+    srcs = ["tags.bzl"],
+    visibility = ["//visibility:public"],
+)