mouse synthesis: don't say the left button is pressed during a release
mouse synthesis: don't say the left button is pressed during a release

Follows the same reasoning as Iefe63cd753f9f8bb04278fd04a4d728e3deda25e
in qtbase: buttons should have only the buttons which are still pressed.

Change-Id: I894df43254eb1b1ce173fd7acc7190e9765beb48
Reviewed-by: Richard Moe Gustavsen <881e230b58d8abf8efbd9b8ce5a2db05f1d53614@digia.com>
Reviewed-by: Frederik Gladhorn <bb2d0c2ba681c116a2d12cf46ffa528dd5dd064e@digia.com>

mgrunditz/qtdeclarative-2d,corngood/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,corngood/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,corngood/qtdeclarative,corngood/qtdeclarative,corngood/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,corngood/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,corngood/qtdeclarative,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative