Define vendor-specific property ro.incremental.enable

[cherry-picking]

Make ro.incremental.enable a vendor-specific property. Allow
system_server and vold to read this property.

Test: manual
BUG: 155212902
Change-Id: I8ff8837af635fa8e7b5bb02e5f6de5ac15b5023b
Merged-In: I8ff8837af635fa8e7b5bb02e5f6de5ac15b5023b
6 files changed