Remove BOOST_PP_IS_EMPTY in favor of BOOST_MPL_PP_TOKEN_EQUAL and added auto as synonym for BOOST_FUSION_ADAPT_AUTO.

Fix ticket https://svn.boost.org/trac/boost/ticket/11157
BOOST_MPL_PP_TOKEN_EQUAL is now used to check if auto/BOOST_FUSION_ADAPT_AUTO
was provided as type, telling to deduce members types.

test/sequence/adapt_struct_named.cpp

@@ -61,13 +61,13 @@ namespace ns
     BOOST_FUSION_ADAPT_STRUCT_NAMED(
         ns::point, point,
         (int, x)
-        (int, y)
-        (BOOST_FUSION_ADAPT_AUTO, z)
+        (BOOST_FUSION_ADAPT_AUTO, y)
+        (auto, z)
     )
 
     // this creates a fusion view: ns1::s1
     struct s { int m; };
-    BOOST_FUSION_ADAPT_STRUCT_NAMED_NS(s, (ns1), s1, (BOOST_FUSION_ADAPT_AUTO, m))
+    BOOST_FUSION_ADAPT_STRUCT_NAMED_NS(s, (ns1), s1, (auto, m))
 
 #endif