More changes.

Add debugging to fdwait. Rewrite getcallerpc on PowerMac to be correct.

Update win to use acme interface directly instead of via pipes. Add comment to pipe about lack of message boundaries.

Move libfmt, libutf into subdirectories of lib9. Add poll-based socket i/o to libthread, so that we can avoid using multiple procs when possible, thus removing dependence on crappy pthreads implementations. Convert samterm, acme to the single-proc libthread. Bring libcomplete, acme up-to-date w.r.t. Plan 9 distribution.

Until I hear otherwise, Refs aren't used enough to merit their own assembly. They are now implemented with locks.