* common/iobuf.c (translate_file_handle): Change the return type to
gnupg_fd_t, not to lose the bits for HANDLE silently.
(do_iobuf_fdopen): Use the type gnupg_fd_t for the first argument.
(do_open): Use do_iobuf_fdopen instead of iobuf_fdopen.
(iobuf_fdopen, iobuf_fdopen_nc): Follow the change of API.