threads merged

[Reini Urban]

I've tested and merged the threads branch today with 6b0fab6 and 637a135.
I've also updated the native_pbc's as I had to bump PBC_COMPAT to 13.0

4.11.0 will not need to bump it again as I plan to merge
rurban/gh870-pmc_class and native_pbc
branches before.
native_pbc will contain code to check pbc against PBC versions not the
parrot library versions.

ChangeLog line:
       + parrot supports now fast and lightweight OS threads, based on
Nat Tucks's
          initial GSoC work on green threads and then Stefan Seifert's extension
          to true parallel OS threads as hybrid threads.
          See http://wknight8111.blogspot.co.at/2010/08/gsoc-threads-chandons-results.html
and
          http://niner.name/Hybrid_Threads_for_the_Parrot_VM.pdf

Current issues:
nqp passes all its tests but cannot yet use lexicals created in other
tasks. nqplexpad is a bit of a mess.
work is ongoing in the nqp branch: gh67-threads. This needs parrot
with threads and rurban/gh870-pmc_class.

Long live perl6
-- 
Reini Urban
http://cpanel.net/   http://www.perl-compiler.org/