QWebsocketHandshakeRequest::readHandshake() fails with IPV6 address

The QWebSocketHandshakeRequest::readHandshake() method is use indexOf(":") to find the port number, but the IPv6 address also uses the same colon notation (e.g http://[some:ipv6::address]:port).
Therefore, we need to find the last colon character to get the port number.

— qwebsockethandshakerequest.cpp 2016-11-28 23:54:05.575851091 +0800
+++ qwebsockethandshakerequest.patch.cpp 2016-11-28 23:53:52.675850649 +0800
@@ -269,7 +269,7 @@
if (m_requestUrl.isRelative()) {
// see http://tools.ietf.org/html/rfc6455#page-17
// No. 4 item in "The requirements for this handshake"

• int idx = host.indexOf(QStringLiteral(":"));
  + int idx = host.lastIndexOf(QStringLiteral(":"));
  bool ok = false;
  int port = 0;
  if (idx != -1) {