Convert libreference-ril to soong am: a9eddd1948

Original change: https://android-review.googlesource.com/c/platform/hardware/ril/+/3283401

Change-Id: I8bf09b37e68b06fb5fff37b86b75e94c95242d48
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>