Revert "Use generic isSelector" am: 27d4f93b76

Original change: https://android-review.googlesource.com/c/platform/external/selinux/+/2858485

Change-Id: Id3421f08cf85f2744b757cdd4e89726f98f1b9a5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>