HEADS UP: you may need to rebuild threaded pkgsrc programs

[Martin Husemann <martin%duskware.de@localhost>]

I just hit my head against the wall trying to make perl configure work
on a random machine I just had updated to realy latest -current untill
I noticed what's going on - so to save you the time and pain, I thought
I better give you all a warning:

Short story: if you have installed new programs using pkgsrc that use
libpthread after the threading model in -current had been changed to 1:1,
you better delete and reinstall them all after upgrading to a very recent
current.

Background: when switching away from SA threads, the userland ABI was
accidently changed slightly by changing the size of pthread_mutex_t.
Now libg++ uses mutexes, so basically every c++ program started being
incompatible. Now that we are about to merge SA support back into -current,
we found this ABI problem, and to easy transitions from 4.0 to 5.0 
Matt Thomas recently fixed it.

However, for everyone using -current in the time in-between, this means
another incompatible ABI change, hence the above recommendation: recompile
everything using threads.

Martin