Fix some compiler warnings.

hardware/asix-sigma/asix-sigma.c

@@ -1038,6 +1038,8 @@ static int receive_data(int fd, int revents, void *session_data)
 
 		bufsz = sigma_read_dram(sigma->state.chunks_downloaded,
 					newchunks, buf, sigma);
+		/* TODO: Check bufsz. For now, just avoid compiler warnings. */
+		(void)bufsz;
 
 		/* Find first ts. */
 		if (sigma->state.chunks_downloaded == 0) {

input/input_binary.c

@@ -31,9 +31,8 @@
 
 static int format_match(const char *filename)
 {
-
 	/* suppress compiler warning */
-	filename = NULL;
+	(void)filename;
 
 	/* this module will handle anything you throw at it */
 	return TRUE;

output/output_csv.c

@@ -126,7 +126,6 @@ static int event(struct sr_output *o, int event_type, char **data_out,
 		 uint64_t *length_out)
 {
 	struct context *ctx;
-	char *outbuf;
 
 	if (!o) {
 		sr_err("csv out: %s: o was NULL", __func__);