Re-format new C++ files

Run tools/format-cpp to format the C++ files introduced in the previous
commit.  Then, run:

    sed -ri 's|^\t \*|     *|' $(find . -name '*.cpp' -o -name '*.hpp')
    sed -ri 's|^\t\t \*|         *|' $(find . -name '*.cpp' -o -name '*.hpp')
    sed -ri 's|^\t\t\t \*|             *|' $(find . -name '*.cpp' -o -name '*.hpp')
    sed -ri 's|^\t\t\t\t \*|                 *|' $(find . -name '*.cpp' -o -name '*.hpp')
    sed -ri 's|^\t\t\t\t\t \*|                     *|' $(find . -name '*.cpp' -o -name '*.hpp')

to fix up the multi-line comments which didn't get un-indented by
clang-format.

Change-Id: Iaf22f898ea5d0839b55d9f1bf09eb3754dc56cf2
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/7105
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>