Fix a typo
Fix bug in sparse file listing

List posix archives containing sparse files >8GB correctly and do not fail.
This fixes also bug in format of listing for sparse files >8GB - now the
real size is printed instead of the effective one (this is not strictly
posix format related).

* src/list.c: Remove redundant assignment.
* src/tar.h: Add new 'real_size' and 'real_size_set' fields in
  tar_stat_info struct.
* src/xheader.c: Correctly handle (especially sparse) file sizes directly in
  xheader_decode().
Add testcase for the previous commit.

* tests/sparse05.at: New file.
* tests/Makefile.am: Add sparse05.at
* tests/testsuite.at: Include sparse05.at
Honor the pax-option overrides when creating archive.

Changes proposed by Denis Excoffier.

* NEWS: Fix typos.
* doc/tar.texi: Fix typos.  Improve recipe for creation of binary
equivalent archives.
* src/create.c (write_extended): Use the value of the
--mtime option (if specified) as the default for exthdr.mtime.
* src/xheader.c (xheader_store): Create the header if at least
one override is supplied in --pax-option.