Work around a Time design flaw.

Because Time is just a thin wrapper around time_t and struct tm, it
has many confusing behaviors. Worse, although the C library reports
errors, Time ignores them. In this instance, bionic returns an error
which Time interprets as 1970-01-01. Now is probably not the time (no
pun intended) to change Time's behavior, so let's just change the
test to avoid stepping on any awkward times.

Longer-term, we should deprecate Time. It has far too many bugs and
bizarre behaviors.

Bug: 8000275
Change-Id: I27e57c09dc977ecbf4c67b18ca84b64fa054a86a