test-fuzz-targets: look for clang-6.0 binary as well
Debian sid is still shipped with clang 4.0 by default. This allows me to
run the test without replacing the system clang to clang-6.0.
#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