Revert "Use generic isSelector" am: 27d4f93b76 am: fd16119838 am: 05a74fd219

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

Change-Id: Ib50610278ec483c87d4d2c52f60ee340744c821b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>