Use one, not zero, as the default lower bound for arrays of AclItems.

Use one, not zero, as the default lower bound for arrays of AclItems.
This avoids changing the displayed appearance of ACL columns now that
array_out decorates its output with bounds information when the lower
bound isn't one.  Per gripe from Gaetano Mendola.  Note that I did not
force initdb for this, although any database initdb'd in the last
couple of days is going to have some problems.