Enable hiddenapi check for exportable stubs am: bd093457e2 am: c32db5a7ad

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2889892

Change-Id: Iefe833af060edbe5696663e34c00f3a6b000f7a5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>