mark unused parameters in signal handlers

Signal handlers receive their signal number as a parameter, but many
don't care what it is (because they only handle one signal, or because
their action is the same regardless of the signal). Mark such parameters
to silence -Wunused-parameter.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/fast-import.c

@@ -436,7 +436,7 @@ static void set_checkpoint_signal(void)
 
 #else
 
-static void checkpoint_signal(int signo)
+static void checkpoint_signal(int signo UNUSED)
 {
 	checkpoint_requested = 1;
 }

builtin/log.c

@@ -436,7 +436,7 @@ static void log_show_early(struct rev_info *revs, struct commit_list *list)
 	setitimer(ITIMER_REAL, &early_output_timer, NULL);
 }
 
-static void early_output(int signal)
+static void early_output(int signal UNUSED)
 {
 	show_early_output = log_show_early;
 }

daemon.c

@@ -928,7 +928,7 @@ static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 		add_child(&cld, addr, addrlen);
 }
 
-static void child_handler(int signo)
+static void child_handler(int signo UNUSED)
 {
 	/*
 	 * Otherwise empty handler because systemcalls will get interrupted

progress.c

@@ -59,7 +59,7 @@ void progress_test_force_update(void)
 }
 
 
-static void progress_interval(int signum)
+static void progress_interval(int signum UNUSED)
 {
 	progress_update = 1;
 }