sepolicies for sys prop enabling flag health check

device_config_flags_health_check_prop is used for enabling/disabling
program flags_health_check which is executed during device booting.
"1" means enabling health check actions in flags_health_check, other
values mean flags_health_check will not perform any action.

Test: build succeeded & manual test
Change-Id: I93739dc5d155e057d72d08fd13097eb63c1193b5
diff --git a/private/property_contexts b/private/property_contexts
index 390c845..0fc3de6 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -165,5 +165,6 @@
 # Properties that relate to server configurable flags
 device_config.reset_performed           u:object_r:device_config_reset_performed_prop:s0
 persist.device_config.attempted_boot_count        u:object_r:device_config_boot_count_prop:s0
+persist.device_config.global_settings.native_flags_health_check_enabled u:object_r:device_config_flags_health_check_prop:s0
 
 apexd.                  u:object_r:apexd_prop:s0