Allow apps to read system_user_mode_emulation_prop.

As it's used by UserManager...

Test: sesearch --allow -s appdomain -t system_user_mode_emulation_prop $ANDROID_PRODUCT_OUT/vendor/etc/selinux/precompiled_sepolicy
Bug: 226643927

Change-Id: I1134a9e0b8ae758e3ebef054b96f9e3237a2401f
diff --git a/private/app.te b/private/app.te
index 5570544..7033cb6 100644
--- a/private/app.te
+++ b/private/app.te
@@ -73,6 +73,9 @@
 # Allow to read db.log.detailed, db.log.slow_query_threshold*
 get_prop(appdomain, sqlite_log_prop)
 
+# Allow to read system_user_mode_emulation_prop, which is used by UserManager.java
+userdebug_or_eng(`get_prop(appdomain, system_user_mode_emulation_prop)')
+
 # Allow font file read by apps.
 allow appdomain font_data_file:file r_file_perms;
 allow appdomain font_data_file:dir r_dir_perms;