Add GL_EXT_discard_framebuffer to QOpenGLExtensions

Change-Id: I57e8dd2ea2e6f018a46eaabed2ca8b6d417358a3
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>
Add NoPartialUpdate support to QOpenGLWidget

[ChangeLog][QtWidgets][QOpenGLWidget] Added an UpdateBehavior flag to
QOpenGLWidget and enabled support for NoParitalUpdate for QOpenGLWidget.
NoPartialUpdate is the default update behavior for QOpenGLWidget.

Task-number: QTBUG-40717
Change-Id: I47d11460e4ef899a24cfd4964ddcac57bc3f91ff
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>
Add Q_DECL_RELAXED_CONSTEXPR to QUuid

Change-Id: I0fa5806ef7a8e14b0728f0b914fa9ffd0dbad811
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>