r320347: ABI breakage for 32-bit powerpc, introduction of 64-bit time_t

[Justin Hibbits]

Hi all,

Thanks to the testing by Andreas Tobler, and others, 32-bit powerpc targets
(powerpc.powerpc, powerpc.powerpcspe) now use a 64-bit time_t.  This is a
significant ABI breakage, and as such should be handled with care.  For
one, live in-place updates cannot be done.  You must install via an
alternate root.  Additionally, all ports, and any local binaries, must be
recompiled with the new ABI, or bad/strange/bizarre things could happen.

The safest route is to perform a clean install.  Second to that, the
following procedure could be used to perform an upgrade:

* Boot to an alternate medium (CD, DVD, memstick, temporary image on swap,
or another hard drive, etc)
* Mount your runtime filesystems to, e.g., /mnt
* pkg remove -a on your runtime system (in chroot)
* Install to /mnt
* Rebuild all ports
* Reboot to new y2038-safe system

- Justin