Merge changes from topic "compact-improvements-v2" into tm-dev

* changes:
  Resend remaining VMAs on partial compaction due to failure
  Add volatile to some cancel compaction signals to avoid compiler optimizations
  Fix for compaction partially bailing out compaction upon cancellation
  Fix for new compactions skipped after cancelling pending compactions
  Improve compaction debugging with extra adb command to force compaction
  Add some trace points to compaction batches and cancellation
  Add threshold to downgrade compaction when swap is low