Remove tools/config/common_settings.bzl. It is unused by Bazel.

RELNOTES:
@bazel_tools//config:common_settings.bzl has been removed.
Use @bazel_skylib//rules:common_settings.bzl instead.
PiperOrigin-RevId: 516377712
Change-Id: I6753edbe12f88f43d582d814679202adb6e1c72f
diff --git a/tools/BUILD b/tools/BUILD
index 15255ba..4102c0a 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -10,7 +10,6 @@
         "//tools/build_defs:srcs",
         "//tools/build_rules:srcs",
         "//tools/compliance:srcs",
-        "//tools/config:srcs",
         "//tools/coverage:srcs",
         "//tools/ctexplain:srcs",
         "//tools/distributions:srcs",
@@ -47,7 +46,6 @@
         "//tools/build_defs:embedded_tools",
         "//tools/build_rules:embedded_tools_srcs",
         "//tools/buildstamp:srcs",
-        "//tools/config:srcs",
         "//tools/coverage:srcs",
         "//tools/cpp:embedded_tools",
         "//tools/genrule:srcs",
@@ -80,7 +78,6 @@
         "//tools/android:bzl_srcs",
         "//tools/build_defs:bzl_srcs",
         "//tools/build_rules:bzl_srcs",
-        "//tools/config:common_settings.bzl",
         "//tools/cpp:bzl_srcs",
         "//tools/jdk:bzl_srcs",
         "//tools/osx:bzl_srcs",
diff --git a/tools/config/BUILD b/tools/config/BUILD
deleted file mode 100644
index b87c7f2..0000000
--- a/tools/config/BUILD
+++ /dev/null
@@ -1,23 +0,0 @@
-# Common config settings and flags.
-#
-# These definitions are only for local use within Bazel built-in tools.
-# In all other cases, use types from github.com/bazelbuild/bazel-skylib.
-
-licenses(["notice"])  # Apache 2.0
-
-filegroup(
-    name = "srcs",
-    srcs = glob(["**"]),
-    visibility = [
-        "//tools:__subpackages__",
-        "@bazel_tools//tools:__subpackages__",
-    ],
-)
-
-exports_files(
-    ["common_settings.bzl"],
-    visibility = [
-        "//tools:__subpackages__",
-        "@bazel_tools//tools:__subpackages__",
-    ],
-)
diff --git a/tools/config/README.md b/tools/config/README.md
deleted file mode 100644
index 3d74a09..0000000
--- a/tools/config/README.md
+++ /dev/null
@@ -1,44 +0,0 @@
-# Common scalar build settings.
-
-## Overview
-
-These definitions are only for use in Bazel built-in tools.  In all
-other cases, use flag type definitions from
-github.com/bazelbuild/bazel-skylib/rules/common_settings.bzl.
-
-<a name="basic-example"></a>
-## Basic Example
-
-### //tools/my_pkg/BUILD
-
-```python
-load("//tools/config:common_settings.bzl", "bool_flag")
-
-bool_flag(
-    name = "experimental_new_behavior",
-    build_setting_default = False,
-)
-```
-
-### //tools/my_pkg/myrule.bzl
-
-```python
-load("//tools/flags:flags.bzl", "BuildSettingInfo")
-
-
-def _myrule_impl(ctx):
-    if ctx.attr._experimental_new_behavior[BuildSettingInfo].value:
-       ...
-    ...
-
-
-myrule = rule(
-    implementation = _myrule_impl.
-    attrs = {
-        ...
-
-        "_experimental_new_behavior": attr.label(
-            default = "//tools/my_pkg:experimental_new_behavior"),
-    },
-)
-```
diff --git a/tools/config/common_settings.bzl b/tools/config/common_settings.bzl
deleted file mode 100644
index 0bb7dd4..0000000
--- a/tools/config/common_settings.bzl
+++ /dev/null
@@ -1,104 +0,0 @@
-# Copyright 2019 The Bazel Authors. All rights reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#    http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-"""Common build setting rules for use in Bazel tools
-
-Warning: The content of this file is copied from
-https://github.com/bazelbuild/bazel-skylib/rules/common_settings.bzl
-We maintain this private copy only to prevent taking a dependency on skylib.
-Please do not innovate make modifications here.
-
-These rules return a BuildSettingInfo with the value of the build setting.
-For label-typed settings, use the native label_flag and label_setting rules.
-
-More documentation on how to use build settings at
-https://bazel.build/rules/config#user-defined-build-settings
-"""
-
-BuildSettingInfo = provider(
-    doc = "A singleton provider that contains the raw value of a build setting",
-    fields = {
-        "value": "The value of the build setting in the current configuration. " +
-                 "This value may come from the command line or an upstream transition, " +
-                 "or else it will be the build setting's default.",
-    },
-)
-
-def _impl(ctx):
-    return BuildSettingInfo(value = ctx.build_setting_value)
-
-int_flag = rule(
-    implementation = _impl,
-    build_setting = config.int(flag = True),
-    doc = "An int-typed build setting that can be set on the command line",
-)
-
-int_setting = rule(
-    implementation = _impl,
-    build_setting = config.int(),
-    doc = "An int-typed build setting that cannot be set on the command line",
-)
-
-bool_flag = rule(
-    implementation = _impl,
-    build_setting = config.bool(flag = True),
-    doc = "A bool-typed build setting that can be set on the command line",
-)
-
-bool_setting = rule(
-    implementation = _impl,
-    build_setting = config.bool(),
-    doc = "A bool-typed build setting that cannot be set on the command line",
-)
-
-string_list_flag = rule(
-    implementation = _impl,
-    build_setting = config.string_list(flag = True),
-    doc = "A string list-typed build setting that can be set on the command line",
-)
-
-string_list_setting = rule(
-    implementation = _impl,
-    build_setting = config.string_list(),
-    doc = "A string list-typed build setting that cannot be set on the command line",
-)
-
-def _string_impl(ctx):
-    allowed_values = ctx.attr.values
-    value = ctx.build_setting_value
-    if len(allowed_values) == 0 or value in ctx.attr.values:
-        return BuildSettingInfo(value = value)
-    else:
-        fail("Error setting " + str(ctx.label) + ": invalid value '" + value + "'. Allowed values are " + str(allowed_values))
-
-string_flag = rule(
-    implementation = _string_impl,
-    build_setting = config.string(flag = True),
-    attrs = {
-        "values": attr.string_list(
-            doc = "The list of allowed values for this setting. An error is raised if any other value is given.",
-        ),
-    },
-    doc = "A string-typed build setting that can be set on the command line",
-)
-
-string_setting = rule(
-    implementation = _string_impl,
-    build_setting = config.string(),
-    attrs = {
-        "values": attr.string_list(
-            doc = "The list of allowed values for this setting. An error is raised if any other value is given.",
-        ),
-    },
-    doc = "A string-typed build setting that cannot be set on the command line",
-)