QIOSTextInputOverlay: compile with Xcode 8 beta / iOS 10

The iOS 10 SDK have introduced a protocol CAAnimationDelegate, which is
required for CAAnimation delegates. So we let our delegate implement it.
Since the SDK is not out yet, we need to support both version 9 and 10
for now.

Change-Id: I2624d8150c39439540a6554cba4921e3b9a2f0cf
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

src/plugins/platforms/ios/qiostextinputoverlay.mm

@@ -299,7 +299,11 @@ static void executeBlockWithoutAnimation(Block block)
 
 // -------------------------------------------------------------------------
 
+#if QT_IOS_PLATFORM_SDK_EQUAL_OR_ABOVE(__IPHONE_10_0)
+@interface QIOSHandleLayer : CALayer <CAAnimationDelegate> {
+#else
 @interface QIOSHandleLayer : CALayer {
+#endif
     CALayer *_handleCursorLayer;
     CALayer *_handleKnobLayer;
     Qt::Edge _selectionEdge;