Offer `core-libart-for-host` under Ravenwood.

Ravenwood is a deviceless testing environment that runs in a host
JVM, similar to Robolectric.

As we're working on onboard existing SystemUI tests that expect
parity with Robolectric, we're needing to offer the same baseline
Robolectric functionality, so we expand the visibility of
`core-libart-for-host` to only the top-level of "//frameworks/base"
which is where Ravenwood.bp is defined.  (We're not exposing the
library to any subpackages.)

Bug: 319647875
Test: atest SystemUiRavenTests
Change-Id: I02185deb302aa764a6970de848d82788f7d07e19

Ravenwood.bp

@@ -97,6 +97,7 @@ android_ravenwood_libgroup {
         "framework-minus-apex.ravenwood",
         "hoststubgen-helper-runtime.ravenwood",
         "hoststubgen-helper-framework-runtime.ravenwood",
+        "core-libart-for-host",
         "all-updatable-modules-system-stubs",
         "junit",
         "truth",

tools/hoststubgen/hoststubgen/helper-framework-runtime-src/libcore-fake/com/android/okhttp/internalandroidapi/Dns.java

+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.okhttp.internalandroidapi;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.List;
+
+/**
+ * A domain name service that resolves IP addresses for host names.
+ * @hide
+ * @hide This class is not part of the Android public SDK API
+ */
+public interface Dns {
+    /**
+     * Returns the IP addresses of {@code hostname}, in the order they should
+     * be attempted.
+     *
+     * @hide
+     */
+    List<InetAddress> lookup(String hostname) throws UnknownHostException;
+}