[rvc] Define vendor-specific property ro.incremental.enable

[already merged in master and AOSP]

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

Test: manual
BUG: 155212902
Merged-In: I8ff8837af635fa8e7b5bb02e5f6de5ac15b5023b
Change-Id: Id432390023de232deb4cc4d0ff3fb73904093b60
diff --git a/private/property_contexts b/private/property_contexts
index 10f029f..b29ef3c 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -249,6 +249,9 @@
 # history size.
 ro.lib_gui.frame_event_history_size u:object_r:bq_config_prop:s0
 
+# Property to enable incremental feature
+ro.incremental.enable      u:object_r:incremental_prop:s0
+
 # Properties to configure userspace reboot.
 init.userspace_reboot.is_supported u:object_r:userspace_reboot_config_prop:s0 exact bool
 init.userspace_reboot.sigkill.timeoutmillis u:object_r:userspace_reboot_config_prop:s0 exact int