build: fix unused-result warnings

Signed-off-by: Thomas Wood <thomas.wood@intel.com>

overlay/gpu-top.c

@@ -29,6 +29,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <assert.h>
 
 #include "perf.h"
 #include "igfx.h"
@@ -260,7 +261,8 @@ static void mmio_init(struct gpu_top *gt)
 		mmio_ring_emit(&render_ring, 1000, payload);
 		mmio_ring_emit(&bsd_ring, 1000, payload);
 		mmio_ring_emit(&blt_ring, 1000, payload);
-		write(fd[1], payload, sizeof(payload));
+		assert(write(fd[1], payload, sizeof(payload))
+		       == sizeof(payload));
 	}
 }
 

overlay/overlay.c

@@ -910,8 +910,8 @@ int main(int argc, char **argv)
 	if (daemonize && daemon(0, 0))
 		return EINVAL;
 
-	if (renice)
-		nice(renice);
+	if (renice && (nice(renice) == -1))
+		fprintf(stderr, "Could not renice: %s\n", strerror(errno));
 
 	signal(SIGUSR1, signal_snapshot);