Statics and threads don't mix well. There can be multiple threads
calling QEvdevTabletHandler::readData() simultaneously if you have
several tablet devices registered with the plugin, creating a race on
the static buffer array.
Make the buffer a simple local variable instead, the array is small
enough that we can afford the per-thread stack allocation.
Change-Id: I4487add8df50743b8178ca6faeb9be45231ccb78
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>