Make QHttpNetworkConnectionPrivate::parseRedirectResponse static

We will use it without holding an instance later. And there's
no reason it is not static already.

Change-Id: I06d455bb2852244c8a4993ea75ceda4e1cb679fb
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/network/access/qhttpnetworkconnection_p.h

@@ -228,7 +228,7 @@ public:
         QUrl redirectUrl;
         QNetworkReply::NetworkError errorCode;
     };
-    ParseRedirectResult parseRedirectResponse(QHttpNetworkReply *reply);
+    static ParseRedirectResult parseRedirectResponse(QHttpNetworkReply *reply);
     // Used by the HTTP1 code-path
     QUrl parseRedirectResponse(QAbstractSocket *socket, QHttpNetworkReply *reply);