lguest: Don't leak /dev/zero fd

Signed-off-by: Mark McLoughlin <[e-mail]>
Signed-off-by: Rusty Russell <[e-mail]>

Documentation/lguest/lguest.c

···
 		    PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, fd, 0);
 	if (addr == MAP_FAILED)
 		err(1, "Mmaping %u pages of /dev/zero", num);
+	close(fd);
 
 	return addr;
 }