Implement boost hash for string_view

include/boost/utility/string_view.hpp

@@ -21,6 +21,7 @@
 #include <boost/detail/workaround.hpp>
 #include <boost/utility/string_view_fwd.hpp>
 #include <boost/throw_exception.hpp>
+#include <boost/container_hash/hash.hpp>
 
 #include <cstddef>
 #include <stdexcept>
@@ -690,6 +691,10 @@ namespace boost {
         }
 #endif
 
+    template <class charT, class traits>
+    std::size_t hash_value(basic_string_view<charT, traits> s) {
+        return boost::hash_range(s.begin(), s.end());
+        }
 }
 
 #if 0