[automerger skipped] Create utility method for calculating supplemental_uid...

[automerger skipped] Create utility method for calculating supplemental_uid from app_uid am: b18fea1a am: ecefb5a0 am: 7ee3d380 -s ours

am skip reason: Merged-In I2b6d6b086985bcb24c837eaa95a937d429d6a583 with SHA-1 1c7acfdb is already in history

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2004993

Change-Id: I7e1782c1d54dd24bb90429a0fc38af23ca9f4565