Use the new AndroidUnwinder object.

Replaces libbacktrace in CallStack. There is one small behavioral
change, the BuildId data is added to the unwinds.

Bug: 120606663

Test: All unit tests pass.
Test: Run the fuzzer for over an hour without any crashes.
Change-Id: Ic8a4247c515ce0d3cdc4d2cc15167d1948b15fa5