imgdiag: add memory page index for dirty entries am: 39d0caf5e5

Original change: https://android-review.googlesource.com/c/platform/art/+/2295219

Change-Id: I5368bbbf49a337c388e84bf261738deb2f76c527
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>