Revert "Revert "Remove cutils threads.h header completely.""

This reverts commit c37838eec8.

Reason for revert: b/296247274 root-cause fixed

Change-Id: I859e7500a1dd09e3a66986cda9e62adf5d7a524a

libcutils/include/cutils/threads.h

@@ -1,15 +0,0 @@
-/*
- * Copyright (C) 2007 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.
- */

libcutils/include_outside_system/cutils/threads.h

@@ -1 +0,0 @@
-../../include/cutils/threads.h