Use nixos path for X server log.

src/main.rs

@@ -35,7 +35,7 @@ fn main() -> Result<()> {
         ],
     };
 
-    let map = screen_mapping_from_xorg_log("/var/log/Xorg.0.log")?;
+    let map = screen_mapping_from_xorg_log("/var/log/X.0.log")?;
     let cmd = run_cmd(&map, cfg)?;
     println!("cmd {:#?}", cmd);