don't detach until the list is going to be modified

removeAt() does detach()'ing for us

Merge-request: 1285
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

(cherry picked from commit 52223d80ec8ba6d579c091efe0e40589a5d2bd67)

Change-Id: I78865e19f989d9079c8dee47b8cf1bdf7e5db261
Reviewed-on: http://codereview.qt-project.org/4578
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

src/corelib/tools/qlist.h

@@ -776,7 +776,6 @@ Q_OUTOFLINE_TEMPLATE int QList<T>::removeAll(const T &_t)
 template <typename T>
 Q_OUTOFLINE_TEMPLATE bool QList<T>::removeOne(const T &_t)
 {
-    detachShared();
     int index = indexOf(_t);
     if (index != -1) {
         removeAt(index);