new glibc pthreads

If you read the libc-alpha list you will see an announcement of a new
pthreads implementation that Ulrich has done for glibc on Linux.  The code
there is now only works with very recent Linux 2.5.x kernel support that
was written in tandem with the new pthreads design.  However, this library
is intended to be portable, will eventually be part of glibc proper, and
will become the fabled one pthreads to rule them all.  

I had hoped to have done something on genericized and Mach-specific code
for this before now, but have been a complete flake on Hurd-related
hacking.  Since no ports have been attempted, the code now surely has some
organization that is overly specific to the one implementation.  But don't
worry, there will be plenty of leeway for reorganizing the source for
portability and generality (in ways that don't degrade the performance of
the optimized cases on Linux).  

I hope that I will get back in the game soon, and then might well do a lot
the Hurd pthreads integration work myself.  (Right now I am waiting for a
serial board in the mail, then will need some more cables, and still have a
borked cross-compilation setup that makes gnumach/oskit kernels that won't
boot and haven't looked into it.  But one of these days...)