Merge "Add libdm and dmctl support for dm-user targets" am: 3042f0ff am:...

Merge "Add libdm and dmctl support for dm-user targets" am: 3042f0ff am: 784ab6ed am: 165a15d4 am: 8214e3e9

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1346622

Change-Id: I00ea4e3cb8d9151dc32181ae6856957461cb2f85