tools: do not distribute development files in tarball

tools: do not distribute development files in tarball

Linters scripts are not useful to have in tarballs, as nobody is
expected to do development outside of a git tree.

Anyway, as of today, don't distribute `.clang-format`, so
`tools/format-cpp.sh` is useless in a tarball as it is.

Change-Id: I9f0aaebbe47390749c9be1085791ae09079519fe
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/13318
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-by: Michael Jeanson <mjeanson@efficios.com>
Tested-by: jenkins <jenkins@lttng.org>