Replaced Set/GetWindowLong with Set/GetWindowLongPtr for 64 bit support

src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs

@@ -699,10 +699,10 @@ namespace Avalonia.Win32.Interop
         public static extern int GetSystemMetrics(SystemMetric smIndex);
 
         [DllImport("user32.dll", SetLastError = true)]
-        public static extern uint GetWindowLong(IntPtr hWnd, int nIndex);
+        public static extern uint GetWindowLongPtr(IntPtr hWnd, int nIndex);
 
         [DllImport("user32.dll", SetLastError = true)]
-        public static extern uint SetWindowLong(IntPtr hWnd, int nIndex, uint value);
+        public static extern uint SetWindowLongPtr(IntPtr hWnd, int nIndex, uint value);
 
         [DllImport("user32.dll", SetLastError = true)]
         public static extern bool GetWindowPlacement(IntPtr hWnd, ref WINDOWPLACEMENT lpwndpl);

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -66,8 +66,8 @@ namespace Avalonia.Win32
         {
             get
             {
-                var style = UnmanagedMethods.GetWindowLong(_hwnd, -16);
-                var exStyle = UnmanagedMethods.GetWindowLong(_hwnd, -20);
+                var style = UnmanagedMethods.GetWindowLongPtr(_hwnd, -16);
+                var exStyle = UnmanagedMethods.GetWindowLongPtr(_hwnd, -20);
                 var padding = new UnmanagedMethods.RECT();
 
                 if (UnmanagedMethods.AdjustWindowRectEx(ref padding, style, false, exStyle))
@@ -219,7 +219,7 @@ namespace Avalonia.Win32
                 return;
             }
 
-            var style = (UnmanagedMethods.WindowStyles)UnmanagedMethods.GetWindowLong(_hwnd, -16);
+            var style = (UnmanagedMethods.WindowStyles)UnmanagedMethods.GetWindowLongPtr(_hwnd, -16);
 
             style |= UnmanagedMethods.WindowStyles.WS_OVERLAPPEDWINDOW;
 
@@ -235,7 +235,7 @@ namespace Avalonia.Win32
             Rect newRect;
             var oldThickness = BorderThickness;
 
-            UnmanagedMethods.SetWindowLong(_hwnd, -16, (uint)style);
+            UnmanagedMethods.SetWindowLongPtr(_hwnd, -16, (uint)style);
 
             if (value)
             {