Assign the iterator returned by std::copy back to Output, so that string algorithms will work with iterators other than inserters

[SVN r62694]

string/test/Jamfile.v2

@@ -59,5 +59,11 @@ test-suite algorithm/string
             :   
             : regex
         ]
+      [ run 
+            find_format_test.cpp
+          : :
+            :   
+            : find_format
+        ]
     ;