Expose Stream.CopyToAsync overload without buffer size

Author: Kristian Hellang

src/System.Runtime/ref/System.Runtime.cs

@@ -5213,6 +5213,7 @@ public void CopyTo(System.IO.Stream destination) { }
         public virtual void CopyTo(System.IO.Stream destination, int bufferSize) { }
         public System.Threading.Tasks.Task CopyToAsync(System.IO.Stream destination) { throw null; }
         public System.Threading.Tasks.Task CopyToAsync(System.IO.Stream destination, int bufferSize) { throw null; }
+        public System.Threading.Tasks.Task CopyToAsync(System.IO.Stream destination, System.Threading.CancellationToken cancellationToken) { throw null; }
         public virtual System.Threading.Tasks.Task CopyToAsync(System.IO.Stream destination, int bufferSize, System.Threading.CancellationToken cancellationToken) { throw null; }
         public virtual void Close() { }
         [System.ObsoleteAttribute("CreateWaitHandle will be removed eventually.  Please use \"new ManualResetEvent(false)\" instead.")]