Include OkHttp source in core_api_files

To enable inclusion in the core library APIs.

Bug: 113148576
Test: build only
Change-Id: I238221de7eaf4df74a81facb661b14ba4a192e52
diff --git a/JavaLibrary.bp b/JavaLibrary.bp
index e88f8ea..4f3e278 100644
--- a/JavaLibrary.bp
+++ b/JavaLibrary.bp
@@ -85,6 +85,7 @@
         ":core_oj_api_files",
         ":core_libart_api_files",
         ":core_simple_java_files",
+        ":okhttp_api_files",
     ],
 }