unit-test.py: ensure TEST_ONLY looked at for all
unit-test.py: ensure TEST_ONLY looked at for all

Noticed that cmake and meson were not honoring this env variable

Tested:
Verified meson based build system acted correctly with this change

Change-Id: I5e98588daf68e2fedcacd61df58d795843931329
Signed-off-by: Andrew Geissler <f7919ac9f8ec0c3ffbc3f483da625c634fd31638@yahoo.com>

openbmc/openbmc-build-scripts,openbmc/openbmc-build-scripts