Added libc++ notes

<p>Within the LLVM 3.2 time-frame there were the following highlights:</p>

<ul>

  <li>...</li>

  <li> C++11 shared_ptr atomic access API (20.7.2.5) has been implemented.</li>

  <li>Applied noexcept and constexpr throughout library.</li>

  <li>Improved C++11 conformance in associative container emplace.</li>

  <li>Performance improvements in: std::rotate algorithm and I/O.</li>

  <li>Operator new/delete and type_infos for exception types moved from libc++ to libc++abi.</li>

  <li>Bug fixes in: <code>&lt;atomic&gt;</code>; vector<code>&lt;bool&gt;</code> algorithms,

    <code>&lt;future&gt;</code>,<code>&lt;tuple&gt;</code>,

    <code>&lt;type_traits&gt;</code>,<code>&lt;fstream&gt;</code>,<code>&lt;istream&gt;</code>,

    <code>&lt;iterator&gt;</code>, <code>&lt;condition_variable&gt;</code>,<code>&lt;complex&gt;</code> as well as visibility fixes.

</ul>

</div>

    <li>The induction variable can be used inside the loop.</li>

    <li>Loop reductions are supported.</li>

    <li>Arrays with affine access pattern do <b>not</b> need to be marked as 'noalias' and are checked at runtime.</li>

    <li>...</li>

    </ul>

</p>