privacy_mode_win_magnifier: fix crash when resolution changed

Signed-off-by: fufesou <shuanglongchen@yeah.net>

src/main.rs

@@ -1,6 +1,6 @@
 // Specify the Windows subsystem to eliminate console window.
 // Requires Rust 1.18.
-#![windows_subsystem = "windows"]
+//#![windows_subsystem = "windows"]
 
 use hbb_common::log;
 use librustdesk::*;