Make copyright comments consistent.

Make copyright comments consistent.

* src/mktemp.c: Update copyright to use newer form.

Make first copyright lines consistent. Some did not end in ", Inc.".
Due to that missing ", Inc" at end of line, emacs' copyright-updating
code missed some opportunities.  This corrects most of those, and
adds some mistakenly omitted years.
* src/chown-core.c: Adjust.
* src/chown-core.h: Likewise.
* src/copy.c: Likewise.
* src/copy.h: Likewise.
* src/cp-hash.c: Likewise.
* src/cp.c: Likewise.
* src/group-list.h: Likewise.
* src/mktemp.c: Likewise.
* src/stat.c: Likewise.
* tests/chmod/equal-x: Likewise.
* tests/dd/skip-seek: Likewise.
* tests/envvar-check: Likewise.
* tests/mv/into-self-2: Likewise.