test_progressbar.c: Fixed wrong null set of timer.
test_progressbar.c: Fixed wrong null set of timer.

If pd is null, pd->timer will crash and cannot set it to null.
This fixes coverity CID 1126081.

rvandegrift/elementary,tasn/elementary,FlorentRevest/Elementary,tasn/elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary,rvandegrift/elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,tasn/elementary,rvandegrift/elementary