Avoid GetObjectsWithTags calls in ClassTrack

We were using GetObjectsWithTags calls in ClassTrack to detect if
classes had been unloaded. This could cause programs to slow down if
they are rapidly receiving events since repeatedly checking all
classes for being unloaded was rather slow. To speed this operation up
we instead use the ObjectFree event to be directly notified when a
class is unloaded.  We then save this information until we are ready
to send an update to the client (during processUnloads).

Test: ./art/tools/run-libjdwp-tests.sh --mode=host
Test: push updated libjdwp.so to marlin
      Attach debugger to AGSA :search process
      Use AGSA

Bug: 79249841
Merged-In: I97ee0fce393d115ee248d0993494891d2c0e4972
Change-Id: I97ee0fce393d115ee248d0993494891d2c0e4972
(cherry picked from commit e039297a3e877b562320a1ead160687944d43c80)
1 file changed