An object, you'll recall, is something between -----BEGIN----- and
-----END----- tags in a directory document.  Some of our code, as
doorss has noted in bug 2352, could assert if one of these ever
overflowed SIZE_T_CEILING but not INT_MAX.  As a solution, I'm setting
a maximum size on a single object such that neither of these limits
will ever be hit.  I'm also fixing the INT_MAX checks, just to be sure.