Allow getwork result to be a bool or JSON object.

The getwork command alters the output depending on whether or not the
optional data parameter was specified.  It is a JSON object when no data
was provided, and a boolean indicating whether a solution was found
when data was provided.

jsonapi.go

@@ -933,10 +933,21 @@ func ReadResultCmd(cmd string, message []byte) (Reply, error) {
 			result.Result = res
 		}
 	case "getwork":
-		var res GetWorkResult
+		// getwork can either return a JSON object or a boolean
-		err = json.Unmarshal(objmap["result"], &res)
+		// depending on whether or not data was provided.  Choose the
-		if err == nil {
+		// right form accordingly.
-			result.Result = res
+		if strings.Contains(string(objmap["result"]), "{") {
+			var res GetWorkResult
+			err = json.Unmarshal(objmap["result"], &res)
+			if err == nil {
+				result.Result = res
+			}
+		} else {
+			var res bool
+			err = json.Unmarshal(objmap["result"], &res)
+			if err == nil {
+				result.Result = res
+			}
 		}
 	case "validateaddress":
 		var res ValidateAddressResult