GraphicsView - add Q_DECL_OVERRIDE to the manual rubber band test

This adds Q_DECL_OVERRIDE to the virtual functions in the test.

Change-Id: If1b7646c9a6f50c6efe2d03d253bd8e0b4c09716
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
Reviewed-by: Laszlo Papp <lpapp@kde.org>
Avoid socket notifiers on invalid file descriptors

There is potential trouble and no point in registering a QSocketNotifier
on an invalid file descriptor. This is prevented now in addition to the
existing warning.

Change-Id: I6fc3c639b167ea98d09a2738986360cc4b3fc210
Reviewed-by: Kevin Krammer <kevin.krammer@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Fixed a typo in the comment.

The orientations involved here can be easy to mix up,
so don't make it more confusing.

Change-Id: I73c4765ebbc89feced12898ac6001eb68db0e21c
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Add qPopulationCount() function, extracted from QBitArray

This functionality is used in multiple places in Qt itself, so it makes
sense to have a global function for this. This also allows to map this
onto specialized assembler instructions, should an architecture provide
them, later on.

Also added comprehensive tests, using a 4-bit lookup-table implementation
as a reference.

Change-Id: I8c4ea72cce54506ebb9fbe61141dbb5f1b7a660f
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
With GCC, use __builtin_popcount{,l,ll} for qPopulationCount()

Change-Id: Ied7a98fa17404f1d9678bfbc1ced4817ab52f40e
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
Fixed a bug where spans across empty cells got broken.

If a row/column is only used only because of the spanning of an item,
the cell should be treated as it didn't exist. We keep track of this
with the "ignore" bit array.

The old code would always start from the row/column at position 1.
In the attached testcase this made the effectiveRowSpan become larger
than actually needed.

Task-number: QTBUG-30255

Change-Id: Ief0e7018ee8e5ee36272ce075a43312ffeac7b91
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>