Rework to avoid problem with Australia/Macquarie on 32-bit hosts.

Problem reported by Alan Gutierrez in
<http://mm.icann.org/pipermail/tz/2013-May/019368.html>.
* australasia (Antarctica/Macquarie): Rework to avoid problem
when combined with older zic + older localtime.
* localtime.c: Rework to avoid problem when combined with
older Antarctica/Macquarie + older zic.
(struct state): New member defaulttype.
(tzload): Set it.
(localsub): Use it.
* zic.c: Rework to avoid problem when combined with
older Antarctica/Macquarie + older zic.
(writezone): Potentially, set type 0 to that of lowest-valued time.
(outzone): Reserve type 0.