bug#12382: Trivial change to have the 'tar' command recognize .xz files for auto-completion in the old shell mode

["Joel Bion" <jpbion@westvi.com>]

DESCRIPTION:

Old shell mode (not E-Shell, but 'M-x shell') does not recognize '.xz' as
a valid tarfile extension. This grows in annoyance as more and more
archives come in this format. This simple patch fixes the problem. The
change itself is five characters big; the rest is NEWS and ChangeLog.

-Joel

DIFFS:

=== modified file 'etc/ChangeLog'
*** etc/ChangeLog       2012-09-04 18:28:39 +0000
--- etc/ChangeLog       2012-09-07 22:06:16 +0000
***************
*** 1,3 ****
--- 1,12 ----
+ 2012-09-07  Joel Bion  <jpbion@westvi.com>
+
+       Add 'xz' as part of valid tarfile regexp; this enables
+       nice things, such as the use of '.xz' filename
+       completion with the 'tar' command in the old shell.
+       * pcmpl-gnu.el: The file with the change.
+       * NEWS: Document the change.
+
+
  2012-09-04  Paul Eggert  <eggert@cs.ucla.edu>

        Give more-useful info on a fatal error (Bug#12328).

=== modified file 'etc/NEWS'
*** etc/NEWS    2012-09-07 10:26:46 +0000
--- etc/NEWS    2012-09-07 22:06:01 +0000
*************** just removing them, as done by `yank-exc
*** 182,187 ****
--- 182,190 ----
  delete-trailing-whitespace command should delete trailing lines at the
  end of the buffer.  It defaults to t.
+
+ ** GNU Emacs old shell 'M-x shell' now supports the .xz extention for
+ tar archives used with the 'tar' command.
+
  ** Search changes

  *** Global `M-s _' starts a symbol (identifier) incremental search,

=== modified file 'lisp/pcmpl-gnu.el'
*** lisp/pcmpl-gnu.el   2012-01-24 18:10:15 +0000
--- lisp/pcmpl-gnu.el   2012-09-07 21:57:41 +0000
***************
*** 128,134 ****
        (pcomplete-uniqify-list rules))))

  (defcustom pcmpl-gnu-tarfile-regexp
!   "\\.t\\(ar\\(\\.\\(gz\\|bz2\\|Z\\)\\)?\\|gz\\|a[zZ]\\|z2\\)\\'"
    "A regexp which matches any tar archive."
    :type 'regexp
    :group 'pcmpl-gnu)
--- 128,134 ----
        (pcomplete-uniqify-list rules))))

  (defcustom pcmpl-gnu-tarfile-regexp
!   "\\.t\\(ar\\(\\.\\(gz\\|bz2\\|Z\\|xz\\)\\)?\\|gz\\|a[zZ]\\|z2\\)\\'"
    "A regexp which matches any tar archive."
    :type 'regexp
    :group 'pcmpl-gnu)