Remove hash_value overload for basic_string_view; it's no longer needed

Author: pdimov

include/boost/core/detail/string_view.hpp

@@ -41,9 +41,6 @@ namespace boost
 // forward declaration of boost::basic_string_view from Utility
 template<class Ch, class Tr> class basic_string_view;
 
-// forward declaration of boost::hash_range from ContainerHash
-template<class It> std::size_t hash_range( It, It );
-
 namespace core
 {
 namespace detail
@@ -1181,11 +1178,6 @@ template<class Ch> class basic_string_view
     }
 
 #endif
-
-    inline friend std::size_t hash_value( basic_string_view const& sv )
-    {
-        return boost::hash_range( sv.begin(), sv.end() );
-    }
 };
 
 // stream inserter