When an error occurs we need to close a file descriptor and unmap a region.
Use a separate label for each cleanup.

Fix CID 182644 (#1-2 of 2): Use after close (USE_AFTER_FREE)8. pass_closed_arg:
Passing closed handle f.fd as an argument to bclose
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>