build-unit-test-docker: sdeventplus will depend on function2

This change is in anticipation of some changes coming to sdeventplus
where it will have a mandatory requirement on function2.

Change-Id: Id00106232701519b5b0e0016887d57d1d08c605b
Signed-off-by: William A. Kennington III <wak@google.com>
1 file changed