Fix NTLM possible data corruption

A mistake in const correctness resulted in the incoming QByteArray
getting modified when it shouldn't. I have no ldea if this could result
in user-visible effects.

Change-Id: Ia0aac2f09e9245339951ffff13c8d8c6b4f909bd
Reviewed-by: Richard J. Moore <rich@kde.org>

src/network/kernel/qauthenticator.cpp

@@ -1078,7 +1078,7 @@ static QByteArray qStringAsUcs2Le(const QString& src)
 }
 
 
-static QString qStringFromUcs2Le(const QByteArray& src)
+static QString qStringFromUcs2Le(QByteArray src)
 {
     Q_ASSERT(src.size() % 2 == 0);
     unsigned short *d = (unsigned short*)src.data();