Fix conditional setting of stdin handle on Windows (#3379)

* Revert 3121353

* Switch to conditional compilation

* Run formatter

* Switch from conditional compilation to compile-time bool

helix-term/src/commands.rs

@@ -4559,7 +4559,7 @@ fn shell_impl(
         .stdout(Stdio::piped())
         .stderr(Stdio::piped());
 
-    if input.is_some() {
+    if input.is_some() || cfg!(windows) {
         process.stdin(Stdio::piped());
     }