Add checkpointing support for A/B updates

This adds implicit rollback support during A/B style updates.
If you explicitly start a checkpoint with -1, needsRollback will
trigger if the update fails, and should be used if any additional
cleanup is needed that is not covered by A/B itself.

Test: All Checkpoint tests pass
Bug: 111020314
Change-Id: I88b4a1098c6bac4dc1438a54c8a8f59577a6c17b
diff --git a/Android.bp b/Android.bp
index b115bc1..af77cef 100644
--- a/Android.bp
+++ b/Android.bp
@@ -39,6 +39,7 @@
     shared_libs: [
         "android.hardware.keymaster@3.0",
         "android.hardware.keymaster@4.0",
+        "android.hardware.boot@1.0",
         "libbase",
         "libbinder",
         "libcrypto",