Merge "Rename system/core/rootdir/Android.mk to create_root_structure.mk" into main am: 1024225b62

Original change: https://android-review.googlesource.com/c/platform/system/core/+/3261831

Change-Id: I6607416db2ff81e12eee1dc1d6234d9d751aba41
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>