Include localedir.h, prepargs.h.

Include localedir.h, prepargs.h.
(long_options): Now static.
(long_options, usage, decode_options): -j is now short for --bzip2,
and -I is now an alias for -T.
(decode_options, main): argv is not const pointer now.
(decode_options): Invoke prepend_default_options to support TAR_OPTIONS.
In diagnostic, mention the string that was the invalid blocking factor,
tape length, group, owner, or record size.
--delete is no longer incompatible with -f -, undoing 2000-01-07 change.
(main): Invoke extract_finish at end of extraction.