Add janitors to the OWNERS file am: 9cb4df1dc5 am: 284793c968

Original change: https://android-review.googlesource.com/c/platform/external/libutf/+/3423594

Change-Id: I3f518ad1f1a88d1ff23bf885ab9f2d96e6c40b68
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>