Fix vertical scrolling with touchpads and trackpoints.

In case of diagonal scrolling, which can happen when using touchpads,
'x' is not zero.

BUG: 425765
FIXED-IN: 20.08.2

src/widgets/TerminalDisplay.cpp

@@ -2850,7 +2850,7 @@ void TerminalDisplay::mouseDoubleClickEvent(QMouseEvent* ev)
 void TerminalDisplay::wheelEvent(QWheelEvent* ev)
 {
     // Only vertical scrolling is supported
-    if (ev->angleDelta().x() != 0) {
+    if (qAbs(ev->angleDelta().y()) < qAbs(ev->angleDelta().x())) {
         return;
     }