AIX pthread patch (preliminary)

[David Edelsohn]

>>>>> Geoff Keating writes:

Geoff> On ELF systems, for instance, all the thread routines from pthread.so
Geoff> are imported weak.  Then before they are used, they are tested to see
Geoff> if their address is 0.  That way, if the application doesn't use
Geoff> pthreads no problems occur.  Can't we do the equivalent thing on AIX?

Geoff> This sort of thing is almost always better than multilibs.  For
Geoff> instance, it allows users to create one version of a (non-threaded)
Geoff> library which will work both with and without pthreads.

	AIX does not have weak symbols / weak imports.  AIX uses a
different C library for pthreads, so one cannot simply link libpthread.a
with lazy binding.


	I have thought about this a little more and I think that we should
flatten out the multilibs:

	common/power/powerpc/ppc64/soft-float with optional /pthread.

That is five or six multilibs.  AIX does not need a soft-float variant of
every other variant.

David