Add @Nullable and @NonNull to intra-core API

We want to annotate methods in the new files in external/conscrypt,
which can only depend on libcore via the intra-core API, so we need
access to these annotations.

Bug: 120475246
Test: make checkbuild
Change-Id: Ie7a7a59a84b2d86db1e9ef4499dd596c75f2bb17
diff --git a/non_openjdk_java_files.bp b/non_openjdk_java_files.bp
index 9a94a14..d711c9d 100644
--- a/non_openjdk_java_files.bp
+++ b/non_openjdk_java_files.bp
@@ -194,6 +194,8 @@
         "luni/src/main/java/libcore/util/EmptyArray.java",
         "luni/src/main/java/libcore/util/HexEncoding.java",
         "luni/src/main/java/libcore/util/NativeAllocationRegistry.java",
+        "luni/src/main/java/libcore/util/NonNull.java",
+        "luni/src/main/java/libcore/util/Nullable.java",
         "luni/src/main/java/libcore/util/SneakyThrow.java",
         "luni/src/main/java/libcore/util/XmlObjectFactory.java",
         "luni/src/main/java/libcore/util/ZoneInfo.java",