make BuilderFieldData package-private, so that SuperBuilder can use it

src/core/lombok/eclipse/handlers/HandleBuilder.java

@@ -105,7 +105,7 @@ public class HandleBuilder extends EclipseAnnotationHandler<Builder> {
 		return ((Boolean) expr).booleanValue();
 	}
 	
-	public static class BuilderFieldData {
+	static class BuilderFieldData {
 		Annotation[] annotations;
 		TypeReference type;
 		char[] rawName;

src/core/lombok/javac/handlers/HandleBuilder.java

@@ -84,7 +84,7 @@ public class HandleBuilder extends JavacAnnotationHandler<Builder> {
 		return ((Boolean) expr).booleanValue();
 	}
 	
-	public static class BuilderFieldData {
+	static class BuilderFieldData {
 		List<JCAnnotation> annotations;
 		JCExpression type;
 		Name rawName;