Merge changes from topics "extdir", "threadvars" am: d2149e6a am: df4ea086 am: 8a05c8df am: 75d6c5ee am: 47754b0f

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1988355

Change-Id: Ib6bf2b74ed7e35492b75b139b3a4b7a995860a48