OSX: remove tablet->mouse event synth

The synthesis of mouse events for unhandled tablet events is now in
cross-platform code, so the platform plugins don't need to do it.

Task-number: QTBUG-47007
Change-Id: I948be398e4b1ab627a8dc97ca20c08dba4390238
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

src/plugins/platforms/cocoa/qcocoaintegration.mm

@@ -341,6 +341,7 @@ QCocoaIntegration::QCocoaIntegration(const QStringList &paramList)
 
     QMacInternalPasteboardMime::initializeMimeTypes();
     QCocoaMimeTypes::initializeMimeTypes();
+    QWindowSystemInterfacePrivate::TabletEvent::setPlatformSynthesizesMouse(false);
 }
 
 QCocoaIntegration::~QCocoaIntegration()

src/plugins/platforms/cocoa/qnsview.h

@@ -140,7 +140,7 @@ Q_FORWARD_DECLARE_OBJC_CLASS(QT_MANGLE_NAMESPACE(QNSViewMouseMoveHelper));
 - (void)otherMouseUp:(NSEvent *)theEvent;
 - (void)handleFrameStrutMouseEvent:(NSEvent *)theEvent;
 
-- (void)handleTabletEvent: (NSEvent *)theEvent;
+- (bool)handleTabletEvent: (NSEvent *)theEvent;
 - (void)tabletPoint: (NSEvent *)theEvent;
 - (void)tabletProximity: (NSEvent *)theEvent;
 

src/plugins/platforms/cocoa/qnsview.mm

@@ -746,7 +746,8 @@ QT_WARNING_POP
 
 - (void)handleMouseEvent:(NSEvent *)theEvent
 {
-    [self handleTabletEvent: theEvent];
+    if ([self handleTabletEvent: theEvent])
+        return;
 
     QPointF qtWindowPoint;
     QPointF qtScreenPoint;
@@ -1152,11 +1153,11 @@ struct QCocoaTabletDeviceData
 typedef QHash<uint, QCocoaTabletDeviceData> QCocoaTabletDeviceDataHash;
 Q_GLOBAL_STATIC(QCocoaTabletDeviceDataHash, tabletDeviceDataHash)
 
-- (void)handleTabletEvent: (NSEvent *)theEvent
+- (bool)handleTabletEvent: (NSEvent *)theEvent
 {
     NSEventType eventType = [theEvent type];
     if (eventType != NSTabletPoint && [theEvent subtype] != NSTabletPointEventSubtype)
-        return; // Not a tablet event.
+        return false; // Not a tablet event.
 
     ulong timestamp = [theEvent timestamp] * 1000;
 
@@ -1169,7 +1170,7 @@ Q_GLOBAL_STATIC(QCocoaTabletDeviceDataHash, tabletDeviceDataHash)
         // Error: Unknown tablet device. Qt also gets into this state
         // when running on a VM. This appears to be harmless; don't
         // print a warning.
-        return;
+        return false;
     }
     const QCocoaTabletDeviceData &deviceData = tabletDeviceDataHash->value(deviceId);
 
@@ -1210,6 +1211,7 @@ Q_GLOBAL_STATIC(QCocoaTabletDeviceDataHash, tabletDeviceDataHash)
                                               deviceData.device, deviceData.pointerType, buttons, pressure, xTilt, yTilt,
                                               tangentialPressure, rotation, z, deviceData.uid,
                                               keyboardModifiers);
+    return true;
 }
 
 - (void)tabletPoint: (NSEvent *)theEvent