Close read-pipe on xdg-mime's side in static.c

Close read-pipe on xdg-mime's side in static.c

The pipe probably doesn't need to be closed since it is closed by
c_simple_http and the forked process stops while it is the only other
thing with that read-pipe-fd. However, it probably would be best to
close it so that during runtime all pipe fd's are closed after use.