run-command: mark unused async callback parameters

The start_async(), etc, functions need a "proc" callback that conforms
to a particular interface. Not every callback needs every parameter
(e.g., the caller might not even ask to open an input descriptor, in
which case there is no point in the callback looking at it). Let's mark
these for -Wunused-parameter.

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

builtin/receive-pack.c

@@ -465,7 +465,7 @@ static void rp_error(const char *err, ...)
 	va_end(params);
 }
 
-static int copy_to_sideband(int in, int out, void *arg)
+static int copy_to_sideband(int in, int UNUSED(out), void *UNUSED(arg))
 {
 	char data[128];
 	int keepalive_active = 0;

convert.c

@@ -619,7 +619,7 @@ struct filter_params {
 	const char *path;
 };
 
-static int filter_buffer_or_fd(int in, int out, void *data)
+static int filter_buffer_or_fd(int UNUSED(in), int out, void *data)
 {
 	/*
 	 * Spawn cmd and feed the buffer contents through its stdin.

fetch-pack.c

@@ -823,7 +823,7 @@ static int everything_local(struct fetch_pack_args *args,
 	return retval;
 }
 
-static int sideband_demux(int in, int out, void *data)
+static int sideband_demux(int UNUSED(in), int out, void *data)
 {
 	int *xd = data;
 	int ret;

send-pack.c

@@ -266,7 +266,7 @@ static int receive_status(struct packet_reader *reader, struct ref *refs)
 	return ret;
 }
 
-static int sideband_demux(int in, int out, void *data)
+static int sideband_demux(int UNUSED(in), int out, void *data)
 {
 	int *fd = data, ret;
 	if (async_with_fork())