added flag for useBatchingForLayoutOutputs experiment

Summary:
Using a config flag to switch between different implementations of transferring layout outputs
- YogaNodeJNI uses multiple access of java fields to pass all properties like width, height, margin etc...
- YogaNodeJNIBatching uses a float array to pass all the data in one java field access

Reviewed By: davidaurelio

Differential Revision: D14378301

fbshipit-source-id: 0da5b28e6a67ad8fd60eb7efe622d9b2deaf177f

java/com/facebook/yoga/YogaConfig.java

@@ -11,6 +11,7 @@ import com.facebook.soloader.SoLoader;
 public class YogaConfig {
 
   public static int SPACING_TYPE = 1;
+  public static boolean useBatchingForLayoutOutputs = false;
 
   long mNativePointer;
   private YogaLogger mLogger;