[Qt][WK2] Implement proxy authentication handling.

[Qt][WK2] Implement proxy authentication handling.
https://bugs.webkit.org/show_bug.cgi?id=78792

Patch by Michael Brüning <michael.bruning@nokia.com> on 2012-02-22
Reviewed by Simon Hausmann.

This patch corrects two bugs with the previous implementation:
1. The signal proxyAuthenticationRequired was not connected to a
   slot.
2. The slot onProxyAuthenticationRequired had the wrong parameters.

* WebProcess/qt/QtNetworkAccessManager.cpp:
(WebKit::QtNetworkAccessManager::QtNetworkAccessManager):
(WebKit::QtNetworkAccessManager::onProxyAuthenticationRequired):
* WebProcess/qt/QtNetworkAccessManager.h: Added include.
(QtNetworkAccessManager):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108499 268f45cc-cd09-0410-ab3c-d52691b4dbfc