virtual display: win10 trivial refactor

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

libs/virtual_display/src/win10/mod.rs

@@ -1,4 +1,9 @@
 pub mod idd;
+use std::ffi::CStr;
 
 pub const DRIVER_INSTALL_PATH: &str = "RustDeskIddDriver/RustDeskIddDriver.inf";
 pub const DRIVER_DOWNLOAD_URL: &str = "";
+
+pub unsafe fn get_last_msg() -> Result<&'static str, std::str::Utf8Error> {
+    CStr::from_ptr(idd::GetLastMsg()).to_str()
+}