Fix windows build (#6774) (#6780)

(cherry picked from commit 2491719f36)

validator/src/main.rs

@@ -533,6 +533,9 @@ pub fn main() {
         option_env!("CI_COMMIT").unwrap_or("unknown")
     );
 
+    let _log_redirect = {
+        #[cfg(unix)]
+        {
             let default_logfile = format!(
                 "solana-validator-{}-{}.log",
                 identity_keypair.pubkey(),
@@ -540,11 +543,9 @@ pub fn main() {
             );
             let logfile = matches.value_of("logfile").unwrap_or(&default_logfile);
 
-    let _log_redirect = if logfile == "-" {
+            if logfile == "-" {
                 None
             } else {
-        #[cfg(unix)]
-        {
                 println!("log file: {}", logfile);
                 Some(gag::Redirect::stderr(File::create(logfile).unwrap_or_else(
                     |err| {
@@ -553,10 +554,11 @@ pub fn main() {
                     },
                 )))
             }
+        }
         #[cfg(not(unix))]
         {
             println!("logging to a file is not supported on this platform");
-            None
+            ()
         }
     };