`@CreatesMustCallFor` should also create an obligation on exceptional successors

Test written by @kelloggm:

 import java.net.*;

 public class BindFail {
   public void test() throws Exception {
     // :: error: required.method.not.called
     Socket s = new Socket();
     SocketAddress addr = new InetSocketAddress("127.0.0.1", 6010);
     try {
       s.bind(addr);
     } catch(Exception e) {
       // socket might still be open on this path
       return;
     }
     s.close();
   }
 }

Socket.bind may open a file descriptor even when it throws an exception; see here. It seems that in general, with @CreatesMustCallFor, we cannot be sure if the method creates the obligation before or after it throws an exception. So, for soundness, we should always create obligations on both normal and exceptional successors.

Start with the BindFail test and its expected required.method.not.called diagnostic. Trace how @CreatesMustCallFor is handled for Socket.bind and how obligations are propagated to exceptional successors. Done means the shown exceptional path is diagnosed while the normal path remains checked.