goprotobuf/README: update example to reflect name change in log package

R=dsymonds
CC=golang-dev
http://codereview.appspot.com/4169049

README

@@ -147,16 +147,16 @@ To create and play with a Test object from the example package,
 		}
 		data, err := proto.Marshal(test)
 		if err != nil {
-			log.Exit("marshaling error:", err)
+			log.Fatal("marshaling error: ", err)
 		}
 		newTest := &example.Test{}
 		err = proto.Unmarshal(data, newTest)
 		if err != nil {
-			log.Exit("unmarshaling error:", err)
+			log.Fatal("unmarshaling error: ", err)
 		}
 		// Now test and newTest contain the same data.
 		if proto.GetString(test.Label) != proto.GetString(newTest.Label) {
-			log.Exit("data mismatch %q %q", proto.GetString(test.Label), proto.GetString(newTest.Label))
+			log.Fatalf("data mismatch %q != %q", proto.GetString(test.Label), proto.GetString(newTest.Label))
 		}
 		// etc.
 	}

proto/lib.go

@@ -145,16 +145,16 @@
 			}
 			data, err := proto.Marshal(test)
 			if err != nil {
-				log.Exit("marshaling error:", err)
+				log.Fatal("marshaling error: ", err)
 			}
 			newTest := new(example.Test)
 			err = proto.Unmarshal(data, newTest)
 			if err != nil {
-				log.Exit("unmarshaling error:", err)
+				log.Fatal("unmarshaling error: ", err)
 			}
 			// Now test and newTest contain the same data.
 			if proto.GetString(test.Label) != proto.GetString(newTest.Label) {
-				log.Exit("data mismatch %q %q", proto.GetString(test.Label), proto.GetString(newTest.Label))
+				log.Fatalf("data mismatch %q != %q", proto.GetString(test.Label), proto.GetString(newTest.Label))
 			}
 			// etc.
 		}