tests: replace `tac` reimplementation by `sort -r`
`sort -r` is better code "formatter" than `tac` since it's
stable. It's also portable so we don't need to reimplement it in
Python.
Differential Revision: https://phab.mercurial-scm.org/D5239
#require clang-format test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
$ cd "$TESTDIR"/..
$ for f in `testrepohg files 'set:(**.c or **.cc or **.h) and not "listfile:contrib/clang-format-ignorelist"'` ; do
> clang-format --style file $f > $f.formatted
> cmp $f $f.formatted || diff -u $f $f.formatted
> rm $f.formatted
> done