More constexpr and noexcept support.

Note 1: Forwarding functions are specified as a C++14 constexpr since
std::forward is not a constexpr within C++11.

Note 2: Though I'm not sure why it doesn't compile, some declarations
are specified as a C++14 constexpr or non-constexpr.

Note 3: Boost.Tuple adaptation and TR1-based tuple implementations are
not constexpr.

include/boost/fusion/view/reverse_view/detail/advance_impl.hpp

@@ -35,7 +35,7 @@ namespace boost { namespace fusion {
                 typedef typename result_of::advance<first_type, negative_dist>::type advanced_type;
                 typedef reverse_view_iterator<advanced_type> type;
 
-                BOOST_FUSION_GPU_ENABLED
+                BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
                 static type
                 call(Iterator const& i)
                 {

include/boost/fusion/view/reverse_view/detail/at_impl.hpp

@@ -30,7 +30,7 @@ namespace boost { namespace fusion { namespace extension
                 result_of::at<typename Seq::seq_type, real_n>::type
             type;
 
-            BOOST_FUSION_GPU_ENABLED
+            BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
             static type
             call(Seq& seq)
             {

include/boost/fusion/view/reverse_view/detail/begin_impl.hpp

@@ -27,7 +27,7 @@ namespace boost { namespace fusion
             {
                 typedef reverse_view_iterator<typename Sequence::last_type> type;
     
-                BOOST_FUSION_GPU_ENABLED
+                BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
                 static type
                 call(Sequence const& s)
                 {

include/boost/fusion/view/reverse_view/detail/deref_data_impl.hpp

@@ -26,7 +26,7 @@ namespace boost { namespace fusion { namespace extension
                 result_of::deref_data<typename It::first_type>::type
             type;
 
-            BOOST_FUSION_GPU_ENABLED
+            BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
             static type
             call(It const& it)
             {

include/boost/fusion/view/reverse_view/detail/deref_impl.hpp

@@ -34,7 +34,7 @@ namespace boost { namespace fusion
                     >::type
                 type;
     
-                BOOST_FUSION_GPU_ENABLED
+                BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
                 static type
                 call(Iterator const& i)
                 {

include/boost/fusion/view/reverse_view/detail/distance_impl.hpp

@@ -33,7 +33,7 @@ namespace boost { namespace fusion {
                 typedef typename Last::first_type last_type;
                 typedef typename result_of::distance<last_type, first_type>::type type;
 
-                BOOST_FUSION_GPU_ENABLED
+                BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
                 static type
                 call(First const& first, Last const& last)
                 {

include/boost/fusion/view/reverse_view/detail/end_impl.hpp

@@ -27,7 +27,7 @@ namespace boost { namespace fusion
             {
                 typedef reverse_view_iterator<typename Sequence::first_type> type;
     
-                BOOST_FUSION_GPU_ENABLED
+                BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
                 static type
                 call(Sequence const& s)
                 {

include/boost/fusion/view/reverse_view/detail/next_impl.hpp

@@ -33,7 +33,7 @@ namespace boost { namespace fusion
     
                 typedef reverse_view_iterator<typename wrapped::type> type;
     
-                BOOST_FUSION_GPU_ENABLED
+                BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
                 static type
                 call(Iterator const& i)
                 {

include/boost/fusion/view/reverse_view/detail/prior_impl.hpp

@@ -33,7 +33,7 @@ namespace boost { namespace fusion
     
                 typedef reverse_view_iterator<typename wrapped::type> type;
     
-                BOOST_FUSION_GPU_ENABLED
+                BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
                 static type
                 call(Iterator const& i)
                 {

include/boost/fusion/view/reverse_view/reverse_view.hpp

@@ -50,14 +50,14 @@ namespace boost { namespace fusion
                 bidirectional_traversal_tag
               , typename traits::category_of<first_type>::type>::value));
 
-        BOOST_FUSION_GPU_ENABLED
+        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
         reverse_view(Sequence& in_seq)
             : seq(in_seq)
         {}
 
-        BOOST_FUSION_GPU_ENABLED
+        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
         first_type first() const { return fusion::begin(seq); }
-        BOOST_FUSION_GPU_ENABLED
+        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
         last_type last() const { return fusion::end(seq); }
         typename mpl::if_<traits::is_view<Sequence>, Sequence, Sequence&>::type seq;
 

include/boost/fusion/view/reverse_view/reverse_view_iterator.hpp

@@ -42,7 +42,7 @@ namespace boost { namespace fusion
                 bidirectional_traversal_tag
               , category>::value));
 
-        BOOST_FUSION_GPU_ENABLED
+        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
         reverse_view_iterator(First const& in_first)
             : first(converter::call(in_first)) {}