Merge "Allow BOARD_BUILD_SYSTEM_ROOT_IMAGE override by command line flag." am: c32d31d4fa am: 9e108ef038 am: 70a9dc84a1 am: e39026b500

Original change: https://android-review.googlesource.com/c/device/generic/common/+/2039603

Change-Id: Ie87cc2eafbf68334402627c3d18570f3f141cc1f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>