Support sparse images in map_file_generator am: 8bd5c4ccde

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2620452

Change-Id: I2806d5a32dd9c297d8e35d7cb63b12d41b02f6d4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>