fop(1), hru(1), intcmp(1), mm(1), rpn(1), swab(1): fixes conditional compilation

src/swab.rs

@@ -54,7 +54,7 @@ fn usage(s: &str) -> ExitCode {
 fn main() -> ExitCode {
 	let argv = args().collect::<Vec<String>>();
 	
-	if cfg!(target_os="openbsd") {
+	#[cfg(target_os="openbsd")] {
 		let promises = Promises::new("stdio");
 		if let Err(e) = pledge(Some(promises), None) {
 			return oserr(&argv[0], e);