Add pirama to OWNERS am: aae2059443

Original change: https://android-review.googlesource.com/c/platform/external/libcxx/+/3046252

Change-Id: I4efb191a0635fd1cc660851ebd286382115b0f45
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>