SSL namespace: Add enum to disable SSL session sharing

There is already an enum to disable SSL session tickets, which has been
used to disable session sharing for now. However, SSL session sharing
is not the same as SSL session tickets: Session sharing is built into
the SSL protocol, while session tickets is a TLS extension (RFC 5077).

Change-Id: If76b99c94b346cfb00e47366e66098f6334fd9bc
Reviewed-by: Richard J. Moore <rich@kde.org>
QAbstractScrollArea - add SizeAdjustPolicy and viewportSizeHint

This patch adds SizeAdjustPolicy to QAbstractScrollArea.
If it is set to AdjustToContents it will make use of the new
protected viewportSizeHint() (BC since it was reserved in Qt5).
This function returns a suggested size based on contents.

Change-Id: I5d8aa517e88b8b21c5712e62b4d574c3aad99d3b
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
Make sure QIconLoader is always initialized

It is necessary to properly initialize the icon loader in all case.
Otherwise some calls might give wrong results if a platform theme plugin
is involved.
For instance, we might miss the actual theme name reported by the
platform theme, eg it's what happen with QStyle::standardPixmap if no
one created a QIcon before its first call.

Also clean up the accesses to the global static and have only
QIconLoader::instance() use it. All other call go through the static
method. This way only instance() needs to call ensureInitialized(),
definitely safer and looks cleaner to me.

Change-Id: Id3ea6816edd5a65586004f69464960abc3602cf8
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>