zed: main: fix unused, remove argsused

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes openzfs#12835

cmd/zed/zed.c

@@ -36,6 +36,7 @@ static volatile sig_atomic_t _got_hup = 0;
 static void
 _exit_handler(int signum)
 {
+	(void) signum;
 	_got_exit = 1;
 }
 
@@ -45,6 +46,7 @@ _exit_handler(int signum)
 static void
 _hup_handler(int signum)
 {
+	(void) signum;
 	_got_hup = 1;
 }