These classes depend only on Core, not Gui.
This allows dropping the dependency of tst_qxmlstream and tst_qzip on
QtGui, and prevents a tst_qxmlstream FTBFS when building with
QT_NO_TEXTODFWRITER.
Symbols move from QtGui to QtCore, but the classes are private API, so
not under BC constraints.
The classes are not used outside qtbase, so no other in-tree users
need porting.
Task-number: QTBUG-3897
Change-Id: Ifa148f43ec139d7f9ac1f3893e2fcf4640e3c60c
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
