[Truffle] Move ModuleChain to its own file.

core/src/main/java/org/jruby/truffle/runtime/ModuleChain.java

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved. This
+ * code is released under a tri EPL/GPL/LGPL license. You can use it,
+ * redistribute it and/or modify it under the terms of the:
+ *
+ * Eclipse Public License version 1.0
+ * GNU General Public License version 2
+ * GNU Lesser General Public License version 2.1
+ */
+package org.jruby.truffle.runtime;
+
+import org.jruby.truffle.runtime.core.RubyModule;
+
+/**
+ * Either an IncludedModule, a RubyClass or a RubyModule.
+ * Private interface, do not use outside RubyModule.
+ */
+public interface ModuleChain {
+    ModuleChain getParentModule();
+
+    RubyModule getActualModule();
+}

core/src/main/java/org/jruby/truffle/runtime/core/RubyModule.java

@@ -27,16 +27,6 @@
 
 import java.util.*;
 
-/**
- * Either an IncludedModule, a RubyClass or a RubyModule.
- * Private interface, do not use outside RubyModule.
- */
-interface ModuleChain {
-    ModuleChain getParentModule();
-
-    RubyModule getActualModule();
-}
-
 /**
  * Represents the Ruby {@code Module} class.
  */