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
diff --git a/private/system_server.te b/private/system_server.te
index 4fc507f..c8e0528 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -680,6 +680,9 @@
 # Read wifi.interface
 get_prop(system_server, wifi_prop)
 
+# Read the vendor property that indicates if Incremental features is enabled
+get_prop(system_server, incremental_prop)
+
 # Create a socket for connections from debuggerd.
 allow system_server system_ndebug_socket:sock_file create_file_perms;