Fix mouse wheel scrolling with libinput

If the Libinput X server input driver is used we get a value for
pixelDelta for a physical mouse wheel scroll, so we check that the
source of the wheel event is actually a mouse, this was fixed in
Qt 5.9.5
https://bugreports.qt.io/browse/QTBUG-59261

Patch by ahmadsamir

BUG: 386762
Differential Revision: https://phabricator.kde.org/D9008

src/ScrollState.cpp

@@ -25,10 +25,21 @@ using namespace Konsole;
 
 void ScrollState::addWheelEvent(const QWheelEvent *wheel)
 {
-    if ((wheel->angleDelta().y() != 0) && (wheel->pixelDelta().y() == 0)) {
-        _remainingScrollPixel = 0;
-    } else {
-        _remainingScrollPixel += wheel->pixelDelta().y();
+    // If the Libinput X server input driver is used we get a value for
+    // pixelDelta for a physical mouse wheel scroll, so we check that
+    // the source of the wheel event is actually a mouse, this has been
+    // fixed upstream in Qt 5.9.5: https://bugreports.qt.io/browse/QTBUG-59261
+    // Fixes Konsole BUG: https://bugs.kde.org/show_bug.cgi?id=386762
+#if (QT_VERSION < QT_VERSION_CHECK(5, 9, 5))
+    if (wheel->source() != Qt::MouseEventNotSynthesized) {
+#else
+    if (true) {
+#endif
+        if ((wheel->angleDelta().y() != 0) && (wheel->pixelDelta().y() == 0)) {
+            _remainingScrollPixel = 0;
+        } else {
+            _remainingScrollPixel += wheel->pixelDelta().y();
+        }
     }
     _remainingScrollAngle += wheel->angleDelta().y();
 }