Switch to libunwind to remove dependency on libgcc for musl am: 441898c285 am: b7ea2f5c7e

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1983628

Change-Id: I4a19e594ee501b2fc88eccd235eb9538930c4bf3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>