SystemTools: Fix MakeDirectory after recent cleanup
SystemTools: Fix MakeDirectory after recent cleanup

The parent commit removed a useless if condition but forgot to leave
behind the behavior from either path.  Add the missing assignment from
the original else block.

Change-Id: I810cce08eb295ff2ba8c2eeff7631178b49c6725

chuckatkins/KWSys,chuckatkins/KWSys,chuckatkins/KWSys,chuckatkins/KWSys