Allow user to set redirect_uri when using QOAuth2AuthorizationCodeFlow

For OAuth 2.0 using QT's networkauth and the new QOAuth2AuthorizationCodeFlow object, I cant set the redirect_uri. When working with google this results in the following authenticate url being sent:

https://accounts.google.com/o/oauth2/auth?client_id=123-abc.apps.googleusercontent.com&redirect_uri=http://localhost:65535/cb&response_type=code&scope=email&state=iEIYn5sN

The setting of redirect_uri to "http://localhost", results in an Error 400 redirect_uri_mismatch from google which is obviously expecting the actual redirect hostname to be provided.

In Qt/5.8/Src/qtnetworkauth/src/oauth/qoauthhttpserverreplyhandler.cpp, the callback address looks hard-coded. The callback() routine in turn used in Qt/5.8/Src/qtnetworkauth/src/oauth/qoauth2authorizationcodeflow.cpp to set the redirectUri value to http://localhost.

Please allow some way for the redirect uri parameter to be set.