- Fixed code to allow decltype implementation of boost::result_of with BOOST_RESULT_OF_USE_DECLTYPE defined.

- Reverted sequence/iterator.hpp to original <correct-no-workaround> version.

[SVN r80396]

test/Jamfile

@@ -12,6 +12,7 @@ project
     : requirements
         <toolset>gcc:<cxxflags>-std=c++0x
         <toolset>darwin:<cxxflags>-std=c++0x
+        <toolset>gcc:<cxxflags>-DBOOST_RESULT_OF_USE_DECLTYPE
     ;
 
 {