Returns a service parse error on overrides across the treble boundary.

Also includes new --out_<partition> flags for
  system,system_ext,product,vendor,odm
to allow host_init_verifier to work with a collection of init rc files.

Test: host_init_verifier --out_system=... --out_vendor=...
      where vendor contains an init rc file that overrides a service
      present in system. Observe parse failure and non-zero exit.
Bug: 163089173
Change-Id: I520fef613e0036df8a7d47a98d47405eaa969110
diff --git a/init/service_parser.cpp b/init/service_parser.cpp
index 97621da..57c311a 100644
--- a/init/service_parser.cpp
+++ b/init/service_parser.cpp
@@ -657,6 +657,14 @@
                            << "' with a config in APEX";
         }
 
+        std::string context = service_->subcontext() ? service_->subcontext()->context() : "";
+        std::string old_context =
+                old_service->subcontext() ? old_service->subcontext()->context() : "";
+        if (context != old_context) {
+            return Error() << "service '" << service_->name() << "' overrides another service "
+                           << "across the treble boundary.";
+        }
+
         service_list_->RemoveService(*old_service);
         old_service = nullptr;
     }