[unity] Fixed a compile error occurring only on Unity 2017, Vector2 not supporting operator* (introduced by commit 758a83a). See #1876.

spine-unity/Assets/Spine/Runtime/spine-unity/Components/RootMotion/SkeletonRootMotionBase.cs

@@ -198,7 +198,7 @@ namespace Spine.Unity {
 				parentBoneScale.x *= scaleBone.ScaleX;
 				parentBoneScale.y *= scaleBone.ScaleY;
 			}
-			localDelta *= parentBoneScale;
+			localDelta = Vector2.Scale(localDelta, parentBoneScale);
 
 			localDelta *= AdditionalScale;
 			localDelta.x *= rootMotionScaleX;