Add missing WIN_ReleaseWndPtr in WIN_CreateDesktopWindow.

windows/win.c

diff --git a/windows/win.c b/windows/win.c
index 6cac7a7..6f21aba 100644
--- a/windows/win.c
+++ b/windows/win.c
@@ -794,7 +794,11 @@
     WIN_SetRectangles( hwndDesktop, &rect, &rect );
     WIN_SetStyle( hwndDesktop, WS_VISIBLE | WS_CLIPCHILDREN | WS_CLIPSIBLINGS );
 
-    if (!USER_Driver.pCreateWindow( hwndDesktop, &cs, FALSE )) return FALSE;
+    if (!USER_Driver.pCreateWindow( hwndDesktop, &cs, FALSE ))
+    {
+        WIN_ReleaseWndPtr( pWndDesktop );
+        return FALSE;
+    }
 
     pWndDesktop->flags |= WIN_NEEDS_ERASEBKGND;
     WIN_ReleaseWndPtr( pWndDesktop );