Mention thread safety feature.

[SVN r12676]

index.htm

@@ -100,6 +100,7 @@ formal reviews of proposed libraries.</p>
   <li><a href="libs/math/octonion/index.html">Octonions</a>: added support for GCC 2.95.x.</a></li>
   <li><a href="libs/smart_ptr/index.htm">Smart Pointers Library</a>: Peter Dimov contributed a new
   implementation that fixes some bugs and adds some features including
+  <a href="libs/smart_ptr/compatibility.htm#threadsafe">thread safety</a> when manipulating the use count,
   <a href="libs/smart_ptr/shared_ptr.htm#constructors">custom delete functions</a>,
   a new <a href="libs/smart_ptr/weak_ptr.htm">weak_ptr</a>, and
   <a href="libs/smart_ptr/shared_ptr.htm#shared_static_cast">shared_static_cast</a>

libs/smart_ptr

@@ -1 +1 @@
-Subproject commit 758954a93f0ac047907ac58c4d3ea0a5df2580b1
+Subproject commit ee3d3bd1e199033c4ee55030aed6aa069ef86e01