Import libatomic_ops-20081024 (version 1.2)

Import libatomic_ops-20081024 (version 1.2)

The latest code is only found in the boehm-gc CVS repository (see
Makefile.version for information).  I had to take this from there,
as there were bug fixes.

This library was imported primarily for the [hopefully]
upcoming audio/pulseaudio package.

TODO: Add support for NetBSD atomic ops?

This package provides semi-portable access to hardware provided
atomic memory operations.  These might allow you to write code:

- That does more interesting things in signal handlers.
- Makes more effective use of multiprocessors by allowing you to write
  clever lock-free code.  Note that such code is very difficult to get
  right, and will unavoidably be less portable than lock-based code.  It
  ia also not always faster than lock-based code.  But it may occasionally
  be a large performance win.
- To experiment with new and much better thread programming paradigms, etc.

As the latest code for this library is only available via CVS, this package
provides a snapshot.