Establish Objective C end-to-end core test with Cronet

src/objective-c/tests/CoreCronetEnd2EndTests/h2_ssl.h

+//
+//  h2_ssl.h
+//  Tests
+//
+//  Created by Muxi Yan on 7/15/16.
+//  Copyright © 2016 gRPC. All rights reserved.
+//
+
+#ifndef h2_ssl_h
+#define h2_ssl_h
+
+
+#endif /* h2_ssl_h */