Fix infinite recursion in float128 hash_value

include/boost/multiprecision/float128.hpp

@@ -632,7 +632,7 @@ inline int eval_signbit BOOST_PREVENT_MACRO_SUBSTITUTION(const float128_backend&
 
 inline std::size_t hash_value(const float128_backend& val)
 {
-   return hash_value(static_cast<double>(val.value()));
+   return boost::multiprecision::detail::hash_value(static_cast<double>(val.value()));
 }
 
 } // namespace backends

test/test_hash.cpp

@@ -34,6 +34,7 @@
 #include <boost/functional/hash.hpp>
 
 #include "test.hpp"
+#include <functional> // std::hash
 #include <iostream>
 #include <iomanip>