Process TOUCH_CANCEL events from libinput individually

This fixes a bug where cancelled touch sequences get ignored
which results in stuck touch focus.

input.cpp

@@ -2326,7 +2326,7 @@ void InputRedirection::setupLibInput()
         connect(conn, &LibInput::Connection::touchDown, m_touch, &TouchInputRedirection::processDown);
         connect(conn, &LibInput::Connection::touchUp, m_touch, &TouchInputRedirection::processUp);
         connect(conn, &LibInput::Connection::touchMotion, m_touch, &TouchInputRedirection::processMotion);
-        connect(conn, &LibInput::Connection::touchCanceled, m_touch, &TouchInputRedirection::cancel);
+        connect(conn, &LibInput::Connection::touchCanceled, m_touch, &TouchInputRedirection::processCancel);
         connect(conn, &LibInput::Connection::touchFrame, m_touch, &TouchInputRedirection::frame);
         auto handleSwitchEvent = [this] (SwitchEvent::State state, quint32 time, quint64 timeMicroseconds, LibInput::Device *device) {
             SwitchEvent event(state, time, timeMicroseconds, device);

touch_input.cpp

@@ -201,6 +201,12 @@ void TouchInputRedirection::processMotion(qint32 id, const QPointF &pos, quint32
     m_windowUpdatedInCycle = false;
 }
 
+void TouchInputRedirection::processCancel()
+{
+    m_touches--;
+    cancel();
+}
+
 void TouchInputRedirection::cancel()
 {
     if (!inited()) {

touch_input.h

@@ -46,6 +46,7 @@ public:
     void processDown(qint32 id, const QPointF &pos, quint32 time, LibInput::Device *device = nullptr);
     void processUp(qint32 id, quint32 time, LibInput::Device *device = nullptr);
     void processMotion(qint32 id, const QPointF &pos, quint32 time, LibInput::Device *device = nullptr);
+    void processCancel();
     void cancel();
     void frame();