Add missing REUSE licenses

Add missing REUSE licenses

`reuse lint` says:

    # MISSING LICENSES

    'FSFAP' found in:
    * m4/ax_append_compile_flags.m4
    * m4/ax_append_flag.m4
    * m4/ax_check_compile_flag.m4
    * m4/ax_cxx_compile_stdcxx.m4
    * m4/ax_require_defined.m4
    'FSFULLR' found in:
    * m4/ae_python_modules.m4
    'GPL-2.0-or-later' found in:
    * m4/ax_c___attribute__.m4
    * m4/ax_pthread.m4
    * tests/utils/tap-driver.sh
    'LicenseRef-Autoconf-exception-macro' found in:
    * m4/ax_c___attribute__.m4
    * m4/ax_pthread.m4

Download and add them.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I71576e2ed2281a1890a49a5cb9261c11fe30706e
Reviewed-on: https://review.lttng.org/c/babeltrace/+/11381
Reviewed-by: Michael Jeanson <mjeanson@efficios.com>