screendump: use qemu_unlink()

Don't attempt to remove /dev/fdset files.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

ui/console.c

@@ -380,7 +380,7 @@ void qmp_screendump(const char *filename, bool has_device, const char *device,
     }
 
     if (!ppm_save(fd, surface, errp)) {
-        unlink(filename);
+        qemu_unlink(filename);
     }
 }