touch: remove support for --file=REF_FILE option

touch: remove support for --file=REF_FILE option

* src/touch.c (main): Remove support for the deprecated, long-named
--file option, which is an alternate name for --reference (-r).
That option was undocumented with the arrival of --reference, in
the 1995-10-29 commit, 8b92864e1d.  Since the 2009-02-09 commit,
ed85df444a, use of --file has elicited a warning.  Not only was
this code due for removal, but the long-name-use-detecting code
was buggy in that it would use a stale or uninitialized "long_idx",
as reported by Robin H. Johnson in http://bugs.gentoo.org/322421.
* NEWS (Changes in behavior): Mention it.