tar

* Adopted package
* Updated
  - pristine-tar.diff (added prototypes)
* Refreshed
  - debian/patches/oldgnu-unknown-mode-bits.patch
  - proper_it_translation.patch
* Dropped patches (fixed/added in upstream):
  - rmt.8-header-wrong.diff
  - fix-for-difflink.at-failure.diff
  - fix-race-in-dirrem01-and-dirrem02.diff
  - elide-reference-to-section-5-manpage.diff
  - zstd.patch
  - Fix-CVE-2018-20482.patch
* Added
  - gcc-10-warnings.diff (various warnings, triggered in gcc 10+ only; each seems harmless)