Merge "remount: Do not allow remounting during checkpoints." into rvc-dev am:...

Merge "remount: Do not allow remounting during checkpoints." into rvc-dev am: 20d78e33 am: 75eb7e69

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/11914026

Change-Id: I9d91b35f4d2cf9103d22c49456e1cc96310434f5