Separate system_ext_service_contexts out of system sepolicy.

Bug: 137712473
Test: boot crosshatch
Change-Id: If483e7a99dc07f082dd0ecd0162a54140a3267de
diff --git a/Android.mk b/Android.mk
index e570247..f8b6803 100644
--- a/Android.mk
+++ b/Android.mk
@@ -321,6 +321,8 @@
     system_ext_property_contexts \
     system_ext_property_contexts_test \
     system_ext_seapp_contexts \
+    system_ext_service_contexts \
+    system_ext_service_contexts_test \
     system_ext_mapping_file \
 
 endif