t0080: turn t-basic unit test into a helper
While t/unit-tests/t-basic.c uses the unit-test framework added in
e137fe3b29 (unit tests: add TAP unit test framework, 2023-11-09), it is
not a true unit test in that it intentionally fails in order to exercise
various codepaths in the unit-test framework. Thus, we intentionally
exclude it when running unit tests through the various t/Makefile
targets. Instead, it is executed by t0080-unit-test-output.sh, which
verifies its output follows the TAP format expected for the various
pass, skip, or fail cases.
As such, it makes more sense for t-basic to be a helper item for
t0080-unit-test-output.sh, so let's move it to
t/helper/test-example-tap.c and adjust Makefiles as necessary.
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>