Fix QNetworkReply::errorString returning an untranslated string

Fix QNetworkReply::errorString returning an untranslated string

The QHttpNetworkConnectionPrivate::errorDetail is supposed to return a
translated string, which is then set as the QNetworkReply error.
The current code incorrectly uses QT_TRANSLATE_NOOP,
which mark the strings for translation, but does not translate them.
The result is that even with a translator loaded those strings are
written in English.

Fixes QTBUG-18382.

Merge-request: 2671
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>
(cherry picked from commit 434686a926a2a6e71f3cdea2508898b7800f7c81)

Change-Id: I8673cef7671d41106f50b75e78394916f3b720c9
Reviewed-on: http://codereview.qt-project.org/4691
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>