Revert "Convert build_flags.mk to build_flags.bzl"

This reverts commit 6954d69b5878239bcb8421c282b5a08acba0f4d2.

Doesn't work with OUT_DIR outside the tree

Test: OUT_DIR=/source/whatever m
Bug: 283278495
Change-Id: I7f2a4cee59174264c563f0a1e9ebb145952ac14d
diff --git a/build_flags.bzl b/build_flags.mk
similarity index 68%
rename from build_flags.bzl
rename to build_flags.mk
index 3481bb6..87fd36c 100644
--- a/build_flags.bzl
+++ b/build_flags.mk
@@ -13,15 +13,10 @@
 # limitations under the License.
 
 # This file defines the build system flags that can be set based on the
-# release configuration.  If at all possible, use aconfig flags instead.
-# This is for things that must be decided at compile time.
+# release configuration for AOSP.  If at all possible, use aconfig flags
+# instead. This is for things that must be decided at compile time.
 
-# Flags should be alphabetical by flag name.
+# Entries should be alphabetical by flag name.
 
-flags = [
-    struct(
-        name = "RELEASE_DEVICE_CONFIG_VALUE_SETS",
-        partitions = ["all"],
-        default = [],
-    ),
-]
+$(call declare-build-flag, all, RELEASE_DEVICE_CONFIG_VALUE_SETS,)
+
diff --git a/release_config_map.bzl b/release_config_map.bzl
deleted file mode 100644
index 085a135..0000000
--- a/release_config_map.bzl
+++ /dev/null
@@ -1,30 +0,0 @@
-# Copyright (C) 2023 The Android Open Source Project
-#
-# 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.
-
-# This file defines the release configs and the flags they set.
-# Currently there are none, but an example would be:
-# config_maps = {
-#   "udc": struct(
-#     release_version = 1,
-#     flags = [
-#       struct(
-#         name = "my_flag",
-#         value = "flag_value",
-#       ),
-#     ],
-#   ),
-# }
-# The list of flags can also be loaded from another file if necessary.
-
-config_maps = {}