remove unnecessary beginPaint and endPaint overrides

QPlatformBackingStore::endPaint does not take a QRegion parameter.
6ce6b8a378b0d97ba950240ffb048a4b7e485235 set the API, but the
platform implementations were not all synced up since then.  There
was anyway no point in overriding beginPaint and endPaint on
platforms which don't need to do anything there.  This fixes
clang warnings of the form
QXcbBackingStore::endPaint hides overloaded virtual function

Change-Id: Id6cd0fc2c831a34576ac2c73eeb0d5741d26e622
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>
Don't send posted events from QWindowSystemInterface::sendWindowSystemEvents

The responsibility of sendWindowSystemEvents() is to process events from
the window system. Historially that logic was part of the QPA/QWS event
dispatcher, which naturally also sent posted events. Through refactoring,
the code at some point ended up in in the QWindowSystemInterface class,
still with the posting of events in place.

This resulted in QPA event dispatchers adopting a pattern of just calling
sendWindowSystemEvents(), as that would cover both posted and window system
events. Other event dispatchers would call sendWindowSystemEvents(), and
then use a base-class implementation from QtCore for processing events,
resulting in two calls to QCoreApplication::sendPostedEvents() per
iteration of processEvents(). This breaks the contract that processEvents
will only process posted events that has been queued up until then.

We fix this entanglement by removing the sendPostedEvents() call from
QWindowSystemInterface::sendWindowSystemEvents() and move it to the
respective event dispatchers. For some EDs it means an explicit call
to sendPostedEvents, while others were already doing sendPostedEvents
though a separate source (GLib), or using a base-class (UNIX/BB), and
did not need an extra call.

We still keep the ordering of the original sendWindowSystemEvents()
function of first sending posted events, and then processing any
window system events.

Task-number: QTBUG-33485
Change-Id: I8b069e76cea1f37875e72a034c11d09bf3fe166a
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>
qdoc: Now reports duplicate page titles better.

Currently, qdoc reports duplicate pages, when it should be reporting
duplicate page titles. Sometimes the duplicate titles actually refer
to the same page, but often they are different pages with the same
title. This update changes the error message to better indicate that
two identical page titles were seen.

A further complication was that the qdoc warnings for these duplate
page title errors were useless when the duplicates were in different Qt5
modules, because the support for file location information in the qdoc
index files was inadequate. This update adds better location information
to each section in the index file. This makes the index files bigger
and will increase qdoc runtimes, hopefully not too much.

Task-number: QTBUG-33506
Change-Id: I35db3c5e1551b9ef748d63377e94453da80c1e26
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Fix spelling in Q_STATIC_ASSERT in qobject_cast

Change-Id: Ibc2b1296bf7eb20e41c1af044797a9a026bed369
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>