Fix stateful handling of invalid UTF-8 straddling buffer borders

When a UTF-8 sequences is too short, QUtf8Functions::fromUtf8 returns
EndOfString. If the decoder is stateful, we must save the state and then
restart it when more data is supplied.

The new stateful decoder (8dd47e34b9b96ac27a99cdcf10b8aec506882fc2)
mishandled the Error case by advancing the src pointer by a negative
number, thus causing a buffer overflow (the issue of the task).

And it also did not handle the len == 0 case properly, though neither
did the older decoder.

Task-number: QTBUG-38939
Change-Id: Ie03d7c55a04e51ee838ccdb3a01e5b989d8e67aa
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Assume unlabelled mouse buttons are default buttons

This patch fixes legacy wheel scrolling for XInput2 drivers that fail to
label mouse buttons correctly.

Task-number: QTBUG-38937
Change-Id: I659890517e749dc0039489e0b7a8c38be1065d33
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Scrolling devices should not override touch or tablet devices

XISelectEvents override any earlier set event mask for the same device
ids. This may cause touch devices to stop reporting touch events if they
export scroll buttons or axis.

The patch checks for each scrolling device if they are also a touch
devices and includes the necessary bitmask if they are, and skips
any devices also recognized as tablet devices as they already capture
all relevant events.

In addition tablet event handling will no longer block handling of wheel
button events for scroll devices with the same device id.

Task-number: QTBUG-38935
Change-Id: Ifd4657beb0a0cebffe89d3470ef2bd605eb3552e
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Fix an off-by-4 error in qHash with CRC32

I tested only the 64-bit build. The 32-bit build was reading garbage
past the end of the strings in some cases.

Change-Id: If6d239754e16a17cc4e8bb71e2b7778429dfa7ba
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>