Do not trigger sharing of return values in the RubyLauncher

* The returned lambda would share its class, and then its superclasses
  including Object and then all constants. At least this is not necessary
  for the RubyLauncher.

Author: eregon

src/main/java/org/truffleruby/language/RubyParsingRequestNode.java

@@ -90,8 +90,9 @@ public Object execute(VirtualFrame frame) {
                 frame.getArguments());
         final Object value = callNode.call(arguments);
 
-        // The return value will be leaked to Java, share it.
-        if (context.getOptions().SHARED_OBJECTS_ENABLED) {
+        // The return value will be leaked to Java, so share it if the Context API is used.
+        // We share conditionally on EMBEDDED to avoid sharing return values used in RubyLauncher.
+        if (context.getOptions().SHARED_OBJECTS_ENABLED && context.getOptions().EMBEDDED) {
             SharedObjects.writeBarrier(context, value);
         }