Merge [57950], [57952] to release. Fixes #3404. Fixes #3456.

[SVN r57959]

doc/src/boost.xml

@@ -622,7 +622,7 @@
          <firstname>Darin</firstname>
          <surname>Adler</surname>
        </author>
-       <librarypurpose>Five smart pointer class templates</librarypurpose>
+       <librarypurpose>Six smart pointer class templates</librarypurpose>
        <librarycategory name="category:memory"/>
      </libraryinfo>
    </library>  

libs/libraries.htm

@@ -635,7 +635,7 @@ of arbitrary data for persistence and marshalling, from Robert Ramey</li>
 <ul>
     <li><a href="pool/doc/index.html">pool</a> - Memory pool management, from
       Steve Cleary.</li>
-    <li><a href="smart_ptr/index.html">smart_ptr</a> - Five smart
+    <li><a href="smart_ptr/index.html">smart_ptr</a> - Six smart
         pointer class templates, from Greg Colvin, Beman Dawes,
         Peter Dimov, and Darin Adler.</li>
     <li><a href="utility/utility.htm">utility</a> - Class <b>noncopyable</b>

libs/smart_ptr

@@ -1 +1 @@
-Subproject commit e94f64039d6f540d1bada3bd422f592bd8733b8c
+Subproject commit 754fd941ee0c30c347eaaf77706c8a797b8fdf18